The invention relates to a real-time acquisition and alternative self-inspection method for rail traffic vehicle velocity. The method comprises the following steps: (1) performing filtering processingto an external sensor pulse signal and a testing self-inspection signal; (2)sending four ways of sensor signals and four ways of self-inspection signals into two channels of an FPGA through a state machine, so as to lead two groups of different pulses to enter two independent channels through changing of states after certain time; (3) for four ways of pulses entering into the two channels, respectively calculating the frequency values and direction values independently in each channel; and (4) through an CPU, judging the frequency values and direction values calculated, judging whether the expected frequency values and direction values of the self-inspections are identical, if yes, showing the internal circuit of the FPGA works normally, if no, the showing the internal circuit of the FPGAworks abnormally. The self-inspection to the acquired sensor pulse frequency values can be performed through the self-inspecting the pulses, so that the frequency values of a plurality of ways of signals can be accurately calculated, and the burden of the CPU can be lightened.