Phytochemical investigation on the herbs of Lycopodium japonicum led to the isolation of a new serratene triterpenoid, 3α,21α-dihydroxy-16-oxoserrat-14-en-24-yl p-coumarate (1), together with two known ones, lycernuic ketone C (2) and tohogenol (3). Their structures were elucidated by extensive spectroscopic methods, including 1D- and 2D-NMR and HR-ESI-MS. The 13C NMR data of tohogenol was first reported.