Abstract: Taking-up position capability of submarine is a capability to take up favorable firing position to ensure certain hitting or acquisition probability of torpedo. Based on the analysis of the key factors ( including the stealth capability and anti-strike capability of submarine , and the detection capability ,attack capability and time of taking up position of target , etc. ) , taking-up position feasibility is discussed with a conclusion that different positions lead to quite different taking-up position capabilities affected by the key factors. Based on Markov chain , a new model of taking-up position capability is established , where the stealth capability , the anti - strike capability , the detection capability , the attack capability , the time of taking-up position , and the relations among all key factors are all considered. This model makes up for the deficiency due to ignoring the influence of each key factor on the taking-up position capability and the relations among the key factors in the conventional model. An example verifies the feasibility of the new model.