Examination of the chemical constituents of the dried leaves of Isodon eriocalyx (Dunn.) Hara led to the isolation of four new diterpenoids, named maoecrystal Q-T (1-4). Their structures were elucidated as $16(R)-methoxymethyl-6{eta},;7{eta}-dihydroxy-7{alpha},20-epoxy-ent-kaur-2,3-ethenylene-1$, 15-dione(1), $1{eta},18-diacetoxy-6{eta},7{eta}-dihydroxy-7{alpha},20-epoxy-ent-kaur-16-en-15-one;(2),;6{eta},;7{eta}-dihydroxy-15{eta}-acetoxy-7{alpha},20-epoxy-ent-kaur-16-en-1-one$ (3) and $7{eta}-hydroxy-6{eta},15{eta}-diacetoxy-1{alpha},11{eta}-acetonide-7{alpha},20-epoxy-ent-kaur-16-ene$ (4), respectively, on the basis of spectroscopic methods. Meanwhile, five known diterpeonids eriocalyxin B (5), maoecrystal B-D (6-8) and trichokaurin (9) were also obtained.