A hybrid-power driving system (100, 200), in which five forward speed ratios are available by switching three synchronizers, comprising: an input shaft (1, 101) having disposed thereon a first driving gearwheel (11, 111), a second driving gearwheel (12, 112), a third driving gearwheel (13, 113), a reverse-gear driving gearwheel (14, 114), a first synchronizer (9, 109), and a second synchronizer (8, 108), wherein the first synchronizer (9, 109) is disposed between the first driving gearwheel (11, 111) and the second driving gearwheel (12, 112), and wherein the second synchronizer (8, 108) is disposed between the third driving gearwheel (13, 113) and the reverse-gear driving gearwheel (14, 114); a first intermediate shaft (4, 104) having disposed thereon a first speed-reducing gearwheel (22, 122), a first driven gearwheel (15, 115), a second driven gearwheel (16, 116), a third driven gearwheel (17, 117), a reverse-gear driven gearwheel (18, 118), and a third synchronizer (10, 110), wherein the third synchronizer (10, 110) is disposed between the first driven gearwheel (15, 115) and the second driven gearwheel (16, 116); a second intermediate shaft (5, 105) having disposed thereon a first idler gearwheel (20, 120) and a second idler gearwheel (21, 121); a first idler shaft (3, 103) having disposed thereon a reverse-gear idler gearwheel (19, 119); a motor shaft (2, 102) for transmitting motor power to the first driving gearwheel (11, 111); and a differential (60, 160) having gearwheels including a second speed-reducing gearwheel (23, 123), wherein (i) the first driving gearwheel (11, 111) meshes with the first driven gearwheel (15, 115), (ii) the second driving gearwheel (12, 112) meshes with the second driven gearwheel (16, 116), (iii) the third driving gearwheel (13, 113) meshes with the third driven gearwheel (17, 117), (iv) the reverse-gear driving gearwheel (14, 114) meshes with the reverse-gear idler gearwheel (19, 119), (v) the reverse-gear driven gearwheel (18, 118) meshes with the reverse-gear idler gearwheel (19, 119), (vi) the first idler gearwheel (20, 120) meshes with the first driven gearwheel (15, 115), (vii) the second idler gearwheel (21, 121) meshes with the second driven gearwheel (16, 116), and (viii) the first speed-reducing gearwheel (22, 122) meshes with the second speed-reducing gearwheel (23, 123). an input shaft (1, 101) having disposed thereon a first driving gearwheel (11, 111), a second driving gearwheel (12, 112), a third driving gearwheel (13, 113), a reverse-gear driving gearwheel (14, 114), a first synchronizer (9, 109), and a second synchronizer (8, 108), wherein the first synchronizer (9, 109) is disposed between the first driving gearwheel (11, 111) and the second driving gearwheel (12, 112), and wherein the second synchronizer (8, 108) is disposed between the third driving gearwheel (13, 113) and the reverse-gear driving gearwheel (14, 114); a first intermediate shaft (4, 104) having disposed thereon a first speed-reducing gearwheel (22, 122), a first driven gearwheel (15, 115), a second driven gearwheel (16, 116), a third driven gearwheel (17, 117), a reverse-gear driven gearwheel (18, 118), and a third synchronizer (10, 110), wherein the third synchronizer (10, 110) is disposed between the first driven gearwheel (15, 115) and the second driven gearwheel (16, 116); a second intermediate shaft (5, 105) having disposed thereon a first idler gearwheel (20, 120) and a second idler gearwheel (21, 121); a first idler shaft (3, 103) having disposed thereon a reverse-gear idler gearwheel (19, 119); a motor shaft (2, 102) for transmitting motor power to the first driving gearwheel (11, 111); and a differential (60, 160) having gearwheels including a second speed-reducing gearwheel (23, 123), wherein (i) the first driving gearwheel (11, 111) meshes with the first driven gearwheel (15, 115), (ii) the second driving gearwheel (12, 112) meshes with the second driven gearwheel (16, 116), (iii) the third driving gearwheel (13, 113) meshes with the third driven gearwheel (17, 117), (iv) the reverse-gear driving gearwheel (14, 114) meshes with the reverse-gear idler gearwheel (19, 119), (v) the reverse-gear driven gearwheel (18, 118) meshes with the reverse-gear idler gearwheel (19, 119), (vi) the first idler gearwheel (20, 120) meshes with the first driven gearwheel (15, 115), (vii) the second idler gearwheel (21, 121) meshes with the second driven gearwheel (16, 116), and (viii) the first speed-reducing gearwheel (22, 122) meshes with the second speed-reducing gearwheel (23, 123).