Two level atoms are injected into ideal cavity one by one to interact with the light field therein which intially is in coherent state. In one-photon transition case, the quadrature variance could be reduced by this means for suitably chosen interaction time t. But there exists some limitation, the squeezing will become worse if the number of times K is too large. In twophoton transition case, for large mean photon tumber N and optimum interaction time t = π/ g2, analytical formula for dependence of quadrature variance on N and K can be obtained. This formula shows that deep squeezing can be achieved by suitably chosen K. And the larger the N is, the stronger the achievable squeezing will be.