Abstract: The intrinsic characteristics of wireless Ad hoc network, such as self-organizing, self-configuration and self-adaptation, make this kind of network an attractive solution in several scenarios in which lack of a fixed infrastructure. How to evaluate the capacity performance becomes one of the hop topics in the research area of wireless Ad hoc networks. In this paper, stochastic geometry and Poisson point process are applied to establish the network model under different medium access control schemes, namely un-slotted, slotted ALOHA, and CSMA. Based on different modulation/coding schemes and assuming channel inversion power control strategy, outage probability and transmission capacity of networks are investigated. The numerical results show that under a constraint of maximum packet error probability, the choices of the modulation and coding schemes that maximize the transmission capacity, depend on the density of transmissions, and that is, the interference level of the network.