Wheat stalk was pyrolyzed under microwave irradiation and different dilute acids pretreatment, and the pyrolytic mixture were extracted with tetrahydrofuran. The effects of dilute acids pretreatment on the yield of tetrahydrofuran-extractable fraction and the selective conversion of wheat stalk under microwave irradiation were investigated. Compositions of extractable fraction were analyzed with gas chromatography/mass spectrometry. The results indicated that acids can remarkably improve the formation of furfural, pyran-2-one, and 2-butenal, etc.