Abstract: An interval censored observation means that X is known either to lie inside an interval (X_L, X_R, or to lie below X_L or above X_R. But, we are not able to observe the exact value of the survival time X at all. This question is different from the usual right censoring, left censoring or double censoring. In this paper, we introduce some recent results about the estimates of unknown distribution function of interval censoring. Our research is also given simultaneously.