Transient numerical analysis of electrical signal injection into the surface CCD is given regarding the potential equilibration method. The analysis is composed of the charging and discharging processes of signal charges, characterized by time intervals TC and TD of the respective input pulses. A concept of setting time TS" explains how the mode of injection converts from the potential equilibration to dynamic injection, and determines a optimum TC . A concept of residual effect of excess charges" is discussed in relation to sampling effect. The procedure to determine a optimum TD is also proposed. It is concluded that the optimum TC and TD for completion of linear charge preset are determined by device geometry (that is, electrode lengths of the CCD input gates), while the TC also depends on the bias condition of the input pulses. The above conclusions can be applied to setting input pulses and the structure of CCD inputs designed for analog signal processing.