The embodiment of the invention discloses a method for generating star hexadecimal optical signals, an optical transmitter and a system. The method comprises the following steps: receiving the optical signals, and dividing the optical signals into a first path of optical signals and a second path of optical signals; receiving a first path of four level signals and a second path of four level signals; modulating the first path of optical signals according to the first path of four level signals to generate a first path of quadrature phase shift keying QPSK optical signals, and modulating the second path of optical signals according to the second path of four level signals to generate a second path of QPSK optical signals; adjusting the phase difference of the first path of QPSK optical signals and the second path of QPSK optical signals to be pi/4; and combining the adjusted first path of QPSK optical signals and the second path of QPSK optical signals to acquire star hexadecimal quadrature amplitude modulation QAM optical signals. The method, the optical transmitter and the system can reduce the optical transmitter cost, simplify the optical transmitter structure, reduce insertionloss and reduce the difficulty of precise synchronization.