The study is to observe the effect of photodynamic therapy (PDT) mediated with new photo sensitizer (5-aminolevulinic acid, ALA) in Fischer 334 rats with 9L glioma glioma and explore its mechanisms. Twenty Fischer 334 rats are implanted 9L cells to brain and randomly subjected to no treatment and PDT treatment (40, 80, 120 J/cm2). After 7-day implantation, rats with PDT treatment are injected ALA at the dose of 300 mg/kg and then receive PDT treatment for 3 h, respectively. All animals are sacrificed after 7-day PDT treatment and the tumor size is measured by Hematoxylin-Eosin (H-E) staining. Immunohistochemical staining for Ki67 and TUNEL staining are used to detect the proliferation of tumor cells and apoptosis, respectively. Different doses of ALA-PDT treatment significantly improves the decreased living status induced by glioma, and significantly reduces gliomas size. These effects depend on the dosage of PDT in some range, but between the two high doses (80 J/cm2 and 120J/cm2), the therapeutic effect has no significantly difference. By detection of tumor cell proliferation and apoptosis respectively, ALA-PDT treatment can lead apoptosis of tumor cells but has no effect on cell proliferation. ALA-PDT can suppress the development of glioma by induction of apoptosis of tumor cells.