From the perspective of improving the accuracy of trigger signal and the reliability of thyristor trigger pulse, this paper mainly researched the reliable trigger of thyristor on magnetic controlled reactor(MCR). The accuracy study of trigger signal involved appending low-pass filter and phase compensation to zero-crossing detection, and setting the trigger timer interrupt levels to DSP. the reliability research of thyristor trigger pulse mainly analyzed the various measures of enhancing the drive capacity of thyristor from the aspect of the trigger pulse amplitude and width, and proposed the reliable trigger technique. The experimental result showed the method is feasible. Finally, provided the thyristor trigger waveform of the MCR in a variety of trigger angle.