thanks for your replay. first of all, i will caculate the system loop transfer function when L,C current gain, slope compensation, loading is given, i will get poles/zeros, Q, and gain, then i will simulate error amplifier transfer function, and also get poles/zeros and gain, at last i will get the overall transfer function, it shows the PM >60 degree, and crossover frequency is 30~50khz which the switching frequency is 1.5Mhz, it seems reasonable stable.
The transient simulaiton also give load transient, and see output voltage setting, it is also ok!
But the test is like that, ans seems the oscillation frequency is above 100khz, is that anything that i ignored or some strange thing happen.
BTW, i have not add error amplifier clampping circuit,the EA circuit is very simple, one stage opamp.