The Vague sets theory was introduced into identification of types of threats to submarine,and a system model was established to identify the types of threats.The affecting weights were obtained from nearest and farthest Vague distances between characteristic parameter vague set of depicting membership degree for threat targets and positive-and-negative Vague sets.The approach degree derived from weighted Vague distance between characteristic parameter vague set and ideal positive-and-negative Vague sets was used to judge the threat target type.A simulation example shows the effectiveness and creditability of the method.