Timely forecasting of the kick risk after a well kick can reduce the waiting time after well shut-in and provide more time for well killing operations. At present, the multiphase flow model is used to simulate and forecast the pit gain and casing pressure. Due to the complexity of downhole conditions, calculation of the multiphase flow model is difficult. In this paper, the time series analysis method is used to excavate the information contained in the time-varying data of pit gain and casing pressure. A forecasting model based on a time series analysis method of pit gain and casing pressure is established to forecast the pit gain and casing pressure after a kick. To divide the kick risk level and achieve the forecasting of the kick risk before and after well shut-in, kick risk analysis plates based on pit gain and casing pressure are established. Three pit gain cases and one casing pressure case are studied, and a comparison between measured data and predicted data shows that the proposed method has high prediction accuracy and repeatability.