Ultra high-velocity collisionless shocks are generated using an ultra-intense laser interacting with foil-gas target,which consists of copper foil and helium gas.The energy of helium ions accelerated by shock and the proton probing image of the shock electrostatic field show that the shock velocity is 0.02c,where c is the light speed.The numerical and theory studies indicate that the collisionless shock velocity exceeding 0.1c can be generated by a laser pulse with picosecond duration and an intensity of 1020 W/cm2.This system may be relevant to the study of mildly relativistic velocity collisionless shocks in astrophysics.