The umbilical almost contact semi invarinnt submanifolds of a new class of almost contact rie-mannian man ifolds are discussed, and some important results about the differential geometry are obtained.

• 本文讨论了一类新的殆切触黎曼流形的全殆切触脐半不变子流形，得到了这类子流形的微分几何方面的重要结果。