Recently, Sautet et al. (Chem. Rev., 2010, 110, 1788-1806) has given a comprehensive discussion on the surface organometallic species. In this review, a state–of–art understanding will be presented for catalysis of olefin metathesis within zeolites, where the active sites are generally distributed in the nanoscale channels instead of surfaces. It covers the generation of the Mo–carbene active sites from the various olefins, the cross metathesis of ethylene and 2–butylene over these Mo–carbene active sites, the effects of the Mo oxidation state and support acidity as well as the influence of the Al content. More studies are expected for the heterogeneous olefin metathesis such as zeolites, which seems more attractive than the homogeneous counterpart from the industrial point of view.