A projection system, comprising: a light source system, configured to sequentially generate primary light of three colors (R, G, B) including first, second and third primary light; a light modulation system comprising at least one light modulator (504, 813, 917) configured to module the primary light; and a control system (507, 816, 920), configured to: divide the time duration of each primary light in each source image frame into a plurality of modulation periods (R1, G1, B1, R2, G2,...) according to the number of gray scales, each respective modulation period having a duration corresponding to a respective gray scale of the respective primary light, sequentially arrange the modulation periods (R1, G1, B1, R2, G2,...) in a sequence wherein the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B) are arranged in ascending order of duration, and wherein each modulation period of the second primary light is arranged between respective modulation periods of the first and third primary light of the same duration, and control the light source system (501, 502, 503) to generate the primary light of the corresponding color in each modulation period (R1, G1, B1, R2, G2,...) according to the sequence of the modulation periods, and control the at least one light modulator to modulate the primary light of the corresponding color in each modulation period, characterized in that the order of the modulation periods (G1, G2,...) of the second primary light is reversed compared to the order of the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B), such that the sequence is arranged so that the longest modulation period of the second primary light is arranged between the shortest modulation periods (R1, B1) of the first and third primary lights (R, B), and the shortest modulation period of the second primary light is arranged between the longest modulation periods (R4, B4) of the first and third primary lights (R, B). a light source system, configured to sequentially generate primary light of three colors (R, G, B) including first, second and third primary light; a light modulation system comprising at least one light modulator (504, 813, 917) configured to module the primary light; and a control system (507, 816, 920), configured to: divide the time duration of each primary light in each source image frame into a plurality of modulation periods (R1, G1, B1, R2, G2,...) according to the number of gray scales, each respective modulation period having a duration corresponding to a respective gray scale of the respective primary light, sequentially arrange the modulation periods (R1, G1, B1, R2, G2,...) in a sequence wherein the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B) are arranged in ascending order of duration, and wherein each modulation period of the second primary light is arranged between respective modulation periods of the first and third primary light of the same duration, and control the light source system (501, 502, 503) to generate the primary light of the corresponding color in each modulation period (R1, G1, B1, R2, G2,...) according to the sequence of the modulation periods, and control the at least one light modulator to modulate the primary light of the corresponding color in each modulation period, characterized in that the order of the modulation periods (G1, G2,...) of the second primary light is reversed compared to the order of the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B), such that the sequence is arranged so that the longest modulation period of the second primary light is arranged between the shortest modulation periods (R1, B1) of the first and third primary lights (R, B), and the shortest modulation period of the second primary light is arranged between the longest modulation periods (R4, B4) of the first and third primary lights (R, B). divide the time duration of each primary light in each source image frame into a plurality of modulation periods (R1, G1, B1, R2, G2,...) according to the number of gray scales, each respective modulation period having a duration corresponding to a respective gray scale of the respective primary light, sequentially arrange the modulation periods (R1, G1, B1, R2, G2,...) in a sequence wherein the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B) are arranged in ascending order of duration, and wherein each modulation period of the second primary light is arranged between respective modulation periods of the first and third primary light of the same duration, and control the light source system (501, 502, 503) to generate the primary light of the corresponding color in each modulation period (R1, G1, B1, R2, G2,...) according to the sequence of the modulation periods, and control the at least one light modulator to modulate the primary light of the corresponding color in each modulation period, characterized in that the order of the modulation periods (G1, G2,...) of the second primary light is reversed compared to the order of the modulation periods (R1, R2,..., B1, B2,...) of the first and third primary lights (R, B), such that the sequence is arranged so that the longest modulation period of the second primary light is arranged between the shortest modulation periods (R1, B1) of the first and third primary lights (R, B), and the shortest modulation period of the second primary light is arranged between the longest modulation periods (R4, B4) of the first and third primary lights (R, B).