Here we propose a model to generate pulse synchronous laser signals based on waveguide coupled microdisk photonic molecules. Through the beating between the symmetric and anti-symmetric modes in the photonic molecules, dual pulse synchronous laser signals are coupled out from two waveguides. We simulate the light field distributions of the modes in the photonic molecules via finite difference time domain (FDTD) method, and compute the frequency differences between the symmetric mode and anti-symmetric transverse magnetic (TM) coupled modes. The frequency differences, which represent the pulse repetition frequency (PRF) of pulse synchronous laser signals, can reach from dozens of GHz to about 1 THz according to the simulation. The numerical results show that the proposed model can generate dual pulse synchronous laser signals with fixed pulse widths and complementary phase which can act as a pulse synchronous laser signal source.