Abstract: An stochastic access algorithm, which can adapt to change of the number of nodes in JTIDS, was proposed based on stochastic theory. First, the invunerability of contention access (CA) and stochastic access (SA) were analyzed mathematically and simulated. Then, the network simulation model of CA and SA was built to verify the rationality of mathematical analysis above. Lastly, the invulnerability of SA was simulated, and the simulation results prove that this algorithm can adapt to network topology change in the battlefiled, and improve reliablity while assure timeliness.