可以用：detective novel
引用萨缪尔·贝克特的作品介绍：
Molloy,for instance,still retains many of the characteristics of a conventional novel—time,place,movement and plot—and is indeed,on one level,a detective novel.
也可以用：detective story
引用英文网站detective-story：
The detective story soon expanded to novel length.
我个人认为用第一个比较好.