We make research on the virtual channels scheduling algorithm based on priority in packet telemetry system. Probability of occupying physical channel and packets losing rate of the virtual channel with the highest priority are considered, on condition that the packet arrival rate contribution is Poisson contribution. Theoretical analysis and simulation results show that when the running time of the scheduling module is long enough, probability of occupying physical channel by the virtual channel with the highest priority converge on a fixed value. Formulas of calculating packets losing rate are also given, which can offer reference to engineering design.