Capacitive division readout anode has the advantages of simple manufacture technology and high spatial resolution. Linearity of the restored image is limited by the relationship between the values of C (charge divide capacitor), Cs (parasitic capacitor), Cd (capacitor introduced by diagonal electrode) and Cp (perimeter capacitor). This paper describes a discrete capacitance matrix to investigate the dependence of image linearity on capacitor ratios, including C/Cs, C/C d and(N-1)C/C p (N is the number of nodes in each row of the capacitance matrix). Results presents that image nonlinearity varies monotonically with C/Cs, C/C d and(N-1)C/Cp. The effect of these capacitors on the linearity of image can be negligible when C/Cs is greater than 100, C/Cd is greater than 10 and (N-1)C/Cp is smaller than 0.1. The reliability of the simulation results is verified by experiments. The RMS nonlinearity of capacitive anode is expected to less than 0.71%.