Abstract: In the field of laser beam parameter measurement and quality evaluation,the study of random error effect upon the measurement precision is of great importance for proper selection of detector and electronic circuitry.On the basis of the popular moment analysis and the concept of laser beam quality factor,the method to analyze such effects is deduced statistically.This method is applied to a supposed laser beam measurement,and the result is obtained by computer simulation.Such data indicate that the random error and noise have no great effect on the measurement precision,so in laser beam measurement in practice,excessive requirements for high performance of small random error amd noise should not be demanded from the measurement sys-tem