As the core equipment of power distribution management, smart meter is becoming the control center of intelligent house. Accurately predicting the replacement number of smart meters is of great significance to effectively reduce the operation and maintenance cost of smart meters and greatly improve the operation security of smart grid. This paper focuses on how to accurately predict the replacement number of smart meters with few samples and insufficient data statistics, and studies the improved gray-Markov model. Firstly, an improved grey model based on weighted average weakening buffer operator modified data predicts the number of smart meter replacements. Markov model is used to optimize the prediction results of the improved grey model, and maximize the prediction accuracy of the replacement number of smart meters. The actual replacement case of smart meters further verifies the validity of this model in predicting the replacement quantity accurately.