Aiming at problem that a Ka-band satellite signal anti-intercept modulation scheme based on weightedtype fractional Fourier transform（ WFRFT） is proposed to solve the problem that Ka-band satellite signal lacks corresponding anti-intercept modulation scheme. The data source is quadrature phase shift keying（ QPSK） mapped on the baseband

and processed by WFRFT. The processed signal is divided into in-phase/quadrature（ I/Q） and multiplied by orthogonal carrier signal to obtain final modulation signal waveform. The simulation results show that the baseband signal and the modulation waveform will change after WFRFT modulation. The correlation coefficient analysis can obtain the quantitative conclusion. When transformation order is 1

correlation coefficient is only0. 034 5

and the signal is almost irrelevant to the original signal waveform. The bit error rate（ BER） analysis of valid users shows that value of transformation order does not affect on reliability of on system.