Ni-like Sm X-ray laser pumped by double short duration pulse was simulated with series code. Simulation results were compared with experiments done by RAL in UK.The curved target and the ununiformity on line focus were also researched. The Optimization in duration, intensity and delay time were done. Using curved target with radius of 200cm and with 85ps duration, 3.4ns delay time, 9% ppulse and 5.82×１０１３Ｗ/c m ２ main pulse intensity, the output X-ray laser energy was also increasing to 10 times in 18mm length single target.