1. A method for estimating a fan life, comprising: providing fans to be checked at a number of M, wherein M is a positive integer; setting a working temperature and a test temperature of a fan, wherein the test temperature is greater than the working temperature; setting an acceleration factor, wherein the acceleration factor has a fixed value; keeping the fans in an operating state under the test temperature, and detecting and recording a number of the damaged fans at intervals of a check time, until N damaged fans are detected, wherein N≧3 and N is a positive integer; simulating a distribution of time points when the fans are damaged with a Weibull distribution model, and calculating a shape parameter (β) and a characteristic life (α) of the Weibull distribution model, wherein the Weibull distribution model is F ( t ) = 1 -  - ( t α ) β and the shape parameter (β) is greater than 1; calculating a life value of the fans at the test temperature by using the shape parameter and the characteristic life; and calculating a life value of the fans at the working temperature by using the acceleration factor.