Considering the undesirable attributes of synthetic fungicides and the availability of Ficus species in China, the stem of Ficus tikoua Bur. was investigated. One new antifungal pyranoisoflavone, 5,3',4'-trihydroxy-2 '',2 ''-dimethylpyrano (5 '',6 '':7,8) isoflavone (1), together with two known isoflavones, wighteone (2) and lupiwighteone (3) (with previously reported antifungal activities), were isolated from ethyl acetate extract by bioassay-guided fractionation. Their structures were determined by spectroscopic analysis, such as NMR (H-1-H-1 COSY, HMQC, HMBC and NOESY), IR, UV and HRMS, as well as ESI-MSn analyses. The antifungal activities of 1-3 against Phytophthora infestans were evaluated by direct spore germination assay, and the IC50 values were 262.442, 198.153 and 90.365 mu g.mL(-1), respectively.