The CoCrAlSiY alloy coating with a Si mass concentration of 0, 2% and 5% was prepared in this work. The effect of Si element on the structure and properties of the alloy powder and coating was analyzed. In addition, the function of Si element on the high temperature performance of the coating was also discussed. The results show that the Si element is mainly distributed in the β phase, whose volume content and distribution have a great influence on the high temperature performance of the coatings. Furthermore, the Si element promotes the change from internal oxidation to external oxidation of alloy and the formation of the protective oxide film. However, the higher Si addition results in a higher PBR value of oxide film, which will increase the oxide film stress. This is not connected to the improvement of the coating thermal shock resistance at high temperatures.