Abstract: This experimental study AA meat chicken body weight and the muscle fiber diameter's correlational dependence, through to the AA meat chicken body weight and the muscle fiber diameter relevant research, analyzes in its growth process the body weight and the muscle fiber diameter change Chooses 100 AA meat chickens, under the raising in cages environment, the free potable water, picks the Slaughters 8 every week from 1-7 week age, altogether slaughters 7 Under the empty stomach condition each week carries on the body weight weighing, and takes the ration musculus pectoralis sample to survey its textile fiber diameter under the microscope, the record correlation data, establishes the body weight and the musculus pectoralis textile fiber diameter regression equation, and screens the best regression The body weight along with the week age change's best regression equation is: y = 438x2+674x+507, R2 is 9972; The muscle fiber diameter along with the week age change's best regression equation is: y =-3979x2+055x+7457, R2 is 9886; The muscle fiber diameter accompanying body heavy change's best regression equation is: y =647Ln(x)-323, R2 is The test result indicated: The musculus pectoralis textile fiber diameter accompanying body heavy increases increases thickly Therefore, by the body weight size estimated that the muscle fiber diameter thick thin effect is