Roundness error is an im por tant index o f the geome tr ic prec ision. The me thod o f eva luating the roundness erro r has som e de fectiveness. W he re fo re, this paper propo ses a new me thod o f eva luating roundness error quick ly and accurate ly, wh ich adopts a nove l im proved genetic algorithm to realize the. quick search of the center o f the reference circ le by genetic pro cess. In order to ensure conve rgence and qu icken conve rg ing speed, a po licy of adaptivem utation and simu la ted annealing is adopted. M eanw hile, no t on ly Rea l number chrom osome gene coding, but adaptive linear m utation and linear crossove r are adopted to im prove prec ision of a lgor ithm s and converg ing speed. The results o f s imu la tion experim ents and app lications dem onstrate that the roundness e rror can be qu ickly eva luated w ith precision by using the proposed algo rithm.