Xylanase is an important enzyme in pulp and paper, food, feed, and textile industries. It is produced by fermentation process with Tricodherma reesei as fungi, which grows on several carbon sources such as cellulose and xylan. Reutealis trisperma (kemiri sunan) have been used for biodiesel production after being mechanically pressed. The solid waste, which is called Reutealis trisperma cake (RTC) contains carbon and nitrogen sources which are valuable to be used for xylanase production by T. reesei. Shake flask systems were used to grow T. reesei in medium consists of RTC and Potato Dextrose Broth (PDB). The systems were maintained at 28°C, 200 rpm at initial pH of 6.0 for 84 hours. Two forms RTC used in this study were natural and alkaline pretreated. The RTC fermentations were performed for different concentration of PDB (15g/L and 20 g/L) and also for different concentration of RTC (13.33 g/L; 16.67 g/L and 20 g/L). Pretreated systems gave better yield of xylanase production compared to natural systems. Higher concentration of PDB for pretreated system was found to yield lower xylanase production. The highest xylanase activity (198.1 U/mL) was obtained in media containing 15 g/L PDB and 20 g/L pretreated RTC.