Solid state reaction is widely used in the synthesis of electrode materials, due to its low cost and good scalability. However, the traditional solid-state reaction is not suitable for the synthesis of materials with multiple elements, such as high entropy or medium entropy materials, due to the poor homogeneity of raw material mixing. Here, we prepared multi-element doped LiNi0.5Mn1.5O4 (medium entropy) cathode material by two step solid state reaction. X-ray diffraction and Raman image show that the homogeneity of multi-element doped LiNi0.5Mn1.5O4 cathode has been greatly improved with this two-step method. As a result, the electrochemical performance is greatly improved, comparing to traditional solid-state reaction. First, the specific capacity at 0.1 C is increased from 126 mAh/g to 137 mAh/g. With a high current density of 10 C, the specific capacity is even increased from 64 mAh/g to 89 mAh/g with this two-step method. Second, the cycle stability is enhanced, with capacity retention of 86% after cycling at 1 C for 500 times (vs. 71% for the one-step method).