It is very important to study and master the rule of incremental forming of magnesium alloys under different process parameters for theoretical and practical application. Therefore, the effects of different possessing parameters including the forming temperature, friction condition and the tool head diameter on the hot single point incremental forming of AZ31B magnesium alloys were studied using the variable angle cone piece as the research object, and the parts’ effective stress, as well as the max thickness reduction ratio and thickness changes as research target by the finite element software ANSYS/LS-DYNA. The results show that the AZ31B magnesium alloy exhibits good single point incremental forming ability when the forming temperature is 250 oC, the static friction coefficient 0.2, the kinetic friction coefficient 0.1 and the tool head diameter in the range of 10~12 mm.