A method for multiuser superposition transmission, comprising: respectively modulating two bit information streams into a first complex symbol sequence and a second complex symbol sequence; performing superposition processing on the first complex symbol sequence and the second complex symbol sequence to generate a third complex symbol sequence, wherein the third complex symbol sequence has a Gray mapping attribute; and forming a sending signal according to the third complex symbol sequence, and sending the sending signal to multiple receivers; wherein performing, according to the first complex symbol sequence and the second complex symbol sequence, superposition processing to generate the third complex symbol sequence comprises: changing, according to the first complex symbol sequence, an argument of the second complex symbol sequence in a complex plane and keeping an amplitude unchanged to acquire a changed symbol sequence; and performing superposition processing on the first complex symbol sequence and the changed symbol sequence to generate the third complex symbol sequence; characterized in that the third complex symbol sequence is presented as one of the followings: P 1 ⋅ x 1 + y 1 ⋅ i + P 2 ⋅ − 1 ⌈ Xstd / 2 ⌉ ⋅ x 2 + − 1 ⌈ Ystd / 2 ⌉ ⋅ y 2 ⋅ i; and P 1 ⋅ x 1 + y 1 ⋅ i + P 2 ⋅ − 1 ⌊ Xstd / 2 ⌋ ⋅ x 2 + − 1 ⌊ Ystd / 2 ⌋ ⋅ y 2 ⋅ i. wherein P 1 ⋅ x 1 + y 1 ⋅ i is the first complex symbol sequence, P 2 ⋅ x 2 + y 2 ⋅ i is the second complex symbol sequence, P 2 ⋅ − 1 ⌈ Xstd / 2 ⌉ ⋅ x 2 + − 1 ⌈ Ystd / 2 ⌉ ⋅ y 2 ⋅ i or P 2 ⋅ − 1 ⌊ Xstd / 2 ⌋ ⋅ x 2 + − 1 ⌊ Ystd / 2 ⌋ ⋅ y 2 ⋅ i is the changed symbol sequence, Xstd + Ystd · i is an unnormalized integral lattice point constellation symbol corresponding to the first complex symbol sequence, and comprises: an Xstd value corresponding to Binary Phase Shift Keying, BPSK, having a value of: {1,-1} and a Ystd value corresponding to the BPSK is 0, an Xstd value and a Ystd value corresponding to Quadrature Phase Shift Keying, QPSK, having each a value of: {1,-1}, an Xstd value and a Ystd value corresponding to 16 Quadrature Amplitude Modulation, 16QAM, having each a value of: {1,-1,3,-3} and an Xstd and a Ystd value corresponding to 64QAM having each a value of: {1,-1,3,-3,5,-5,7,-7}, P 1 is the first power factor, P 2 is the second power factor, ┌·┐ represents rounding up, and └·┘ represents rounding down. respectively modulating two bit information streams into a first complex symbol sequence and a second complex symbol sequence; performing superposition processing on the first complex symbol sequence and the second complex symbol sequence to generate a third complex symbol sequence, wherein the third complex symbol sequence has a Gray mapping attribute; and forming a sending signal according to the third complex symbol sequence, and sending the sending signal to multiple receivers; wherein performing, according to the first complex symbol sequence and the second complex symbol sequence, superposition processing to generate the third complex symbol sequence comprises: changing, according to the first complex symbol sequence, an argument of the second complex symbol sequence in a complex plane and keeping an amplitude unchanged to acquire a changed symbol sequence; and performing superposition processing on the first complex symbol sequence and the changed symbol sequence to generate the third complex symbol sequence; characterized in that the third complex symbol sequence is presented as one of the followings: P 1 ⋅ x 1 + y 1 ⋅ i + P 2 ⋅ − 1 ⌈ Xstd / 2 ⌉ ⋅ x 2 + − 1 ⌈ Ystd / 2 ⌉ ⋅ y 2 ⋅ i; and P 1 ⋅ x 1 + y 1 ⋅ i + P 2 ⋅ − 1 ⌊ Xstd / 2 ⌋ ⋅ x 2 + − 1 ⌊ Ystd / 2 ⌋ ⋅ y 2 ⋅ i. wherein P 1 ⋅ x 1 + y 1 ⋅ i is the first complex symbol sequence, P 2 ⋅ x 2 + y 2 ⋅ i is the second complex symbol sequence, P 2 ⋅ − 1 ⌈ Xstd / 2 ⌉ ⋅ x 2 + − 1 ⌈ Ystd / 2 ⌉ ⋅ y 2 ⋅ i or P 2 ⋅ − 1 ⌊ Xstd / 2 ⌋ ⋅ x 2 + − 1 ⌊ Ystd / 2 ⌋ ⋅ y 2 ⋅ i is the changed symbol sequence, Xstd + Ystd · i is an unnormalized integral lattice point constellation symbol corresponding to the first complex symbol sequence, and comprises: an Xstd value corresponding to Binary Phase Shift Keying, BPSK, having a value of: {1,-1} and a Ystd value corresponding to the BPSK is 0, an Xstd value and a Ystd value corresponding to Quadrature Phase Shift Keying, QPSK, having each a value of: {1,-1}, an Xstd value and a Ystd value corresponding to 16 Quadrature Amplitude Modulation, 16QAM, having each a value of: {1,-1,3,-3} and an Xstd and a Ystd value corresponding to 64QAM having each a value of: {1,-1,3,-3,5,-5,7,-7}, P 1 is the first power factor, P 2 is the second power factor, ┌·┐ represents rounding up, and └·┘ represents rounding down. an Xstd value corresponding to Binary Phase Shift Keying, BPSK, having a value of: {1,-1} and a Ystd value corresponding to the BPSK is 0, an Xstd value and a Ystd value corresponding to Quadrature Phase Shift Keying, QPSK, having each a value of: {1,-1}, an Xstd value and a Ystd value corresponding to 16 Quadrature Amplitude Modulation, 16QAM, having each a value of: {1,-1,3,-3} and an Xstd and a Ystd value corresponding to 64QAM having each a value of: {1,-1,3,-3,5,-5,7,-7}, P 1 is the first power factor, P 2 is the second power factor, ┌·┐ represents rounding up, and └·┘ represents rounding down.