The porous nickel hydrazine nitrate(NHN) was obtained by in-situ liquid-solid reaction of ammonium salt, hydrazine hydrate and porous nickel under constant temperature in half-closed environment. The detonation velocities of NHN with different mass increase rate were measured using optical fiber time measurement method. Results show detonation velocity is maximum(about 2300 m·s^-1) when the mass increase rate ranges from 35% to 40%. The optimum reaction condition to obtain NHN with high detonation velocity was investigated by orthogonal test. It is found when the concentration of hydrazine hydrate is 0.256 mol·L^-1, and the concentration of ammonium nitrate 0.192 mol·L^-1, and reaction temperature 65 ℃ and pH 9, the detonation velocity of NHN reaches up to 2357-2499 m·s^-1.