Abstract: The space charge effect is the core problem of high intensity proton accelerator, especially at injection and initial acceleration stages. Using the phase space painting with optimized process, will effectively reduce the influence of space charge effect on injection and acceleration efficiency, and emittance increase. Transverse phase space painting methods can be divided into correlated painting and anti-correlated painting. In this paper, firstly, the transverse phase space paintings for the high intensity proton synchrotron are discussed in detail, including different painting methods and different implementation methods. Secondly, based on the injection system of the China Spallation Neutron Source (CSNS), the beam injection process and anti-correlated painting design scheme are studied in detail. The reasons for the reduction of the actual vertical painting range and the influence of edge focusing effects of the bump magnets on the painting and beam dynamics are deeply explored. In addition, the method to perform the correlated painting based on the mechanical structure of the anti-correlated painting scheme and its key role in realizing the CSNS design goal are briefly introduced. Finally, according to the requirement of switching between different painting methods online in future accelerators, a new injection scheme that can realize correlated and anti-correlated painting simultaneously has been proposed. The new painting injection scheme has been demonstrated, simulated and optimized in detail.