The calculation of order parameteres with variant temperature in Ll2 structure has been carried out in this work by means of Monte Carlo method statistical physics. The order interaction of the nearest neighbour J1 and three kinds of order interaction of next neares' neighbour J2= 0, - 0.3J1 as well as 0.3J1 were considered in this calculation. The results show that the calculation value of the critical temperature Tc (order-disorder transition temperature) of the first order phase transformation is in good agreement with that obtained by some other theories, such as quasi-chemical method; and Tc is sensitively affected by J2, that may be regarded as an interpretation about the action of interstitial atoms in Ll2 structure.