中文摘要：

设M=（P_1×I）∪_F（P_2×I）,其中P_i（i=1,2）是可定向的闭曲面,I是单位闭区间,F是M中的不可压缩四穿孔球面,本文通过F在P_1和P_2上的一类可能分离形式,给出了g（M）=g（P_1）＋g（P_2）的充分性条件,证明了乘积流形一类四穿孔球面和具有亏格可加性.

英文摘要：

Suppose M=（P_1×I）∪_F（P_2×I）, where P, （i=1,2） is an oriented closed surface, I is theunit interval, F is an incompressible foul punctured sphere in M, by the separating form of F in P1 and P2, we prove that g（M） =g（P1） if-g（P2）, which gives the additivity of Heegaard genera of four punctured sphere sum of product 3-manifolds.