A theoritical study of the reaction rate control step on the carbonlation of methanol to acetic acid catalyzed by copolymercoordinated rhodium has been investigated in terms of the ASED MO method(including atomic repellent energy).The energy barriers of oxidative addition reactions for different systems were calculated.The way of electron transfer and space factor influencing the activation energies during oxidative addition were studied.It showed that the calculating results were bassically in agreement with the experimental results.The differences of catalysis activity between 2-vinylpridine system and 4-vinylpridine system were explained theoretically.