The atmospheric plasma spraying (APS) is used to prepare Ni/Al adhering coating, and flame spraying is used to prepare NiCrAl/Diatomite sealing coating. The effects on growth rates and hardness of coating from distance of spraying, powder feeding rate, flame current, spray angle and oxygen-fuel ratio are studied. Result shows that, when the oxygen-fuel ratio is less than 1.6, along with the raise of spraying distance, the coatings growth rate is lower and the hardness goes up after keeps still. When the O₂:C₂H₂ > 1.6, the growth rate goes up first, then goes down, and hardness turns low gradually. Along with the increase of gun moving speed, coatings growth rate goes down a little, while hardness goes up a little. The increase of flow current increases the growth rate and decreases the hardness. Along with the increase of powder feeding rate, the coatings growth rate increases obviously, and the hardness goes up and then down.