Objective To develop MSNs loaded with ICG and investigate its diagnostic value and photodynamic therapeutic value in the experimental pancreatic cancer. Methods ICG was loaded into MSNs to prepare the ICG/MSNs probe. The probe toxicity was evaluated by MTT assays. Near?infrared stereo fluores?cence microscope ( NISFM) was applied to investigate whether the ICG/MSNs would be uptaken by the human pancreatic cancer cells. After incubated with PBS, ICG (10μg/ml), MSNs or ICG/MSNs (10μg/ml ICG) for 24 h and treated with photodynamic therapy (PDT, (780±25) nm laser, 500 mW/cm2), the human pancreatic cancer cells survival rate was determined by MTT method. The human pancreatic cancer cells were implanted into nude mice to prepare subcutaneous tumor models. The distribution of ICG/MSNs in sub?cutaneous tumor models was studied with in vivo imaging system ( IVIS ) . With reference to the injection dose of ICG(0.5 mg/kg), the mice in PBS group, ICG group, ICG/MSNs group (4 mice per group) were injected via tail vein with 150μl PBS, ICG solution and ICG/MSNs solution, respectively. After treated by PDT for 48 h, the mice were observed by IVIS for 2 weeks using BLI to evaluate the therapeutic effect of PDT. NISFM was used to observe the fluorescence in tumor region. One?way analysis of variance was used to analyze the data. Results The diameter of ICG/MSNs was about 100 nm and it could be uptaken by human pancreatic cancer cells. After treated by PDT, the survival rates of human pancreatic cancer cells were (24?5±5.0)%, (81.2±1.6)%, (90.7±2.0)% and (93.4±1.7)% in ICG/MSNs group, ICG group, MSNs group and PBS group, respectively(F=212.289, P<0.05). ICG/MSNs group showed better therapeutic effect than ICG group( P<0.05) . After 12 d treated by PDT, the tumor did not recur or grow in ICG/MSNs group, but grew obviously in ICG group and PBS group. The BLI of tumor area in PBS group, ICG group and ICG/MSNs group were (61.2±7.7)×108, (56.7±9.0)×108 and (2.4±1.5)×108, respectively(F=67?098, P<0.05) . And the difference between ICG/MSNs and ICG group was statistically significant ( P<0.05) . Meanwhile, the NISFM showed clearly the tumor location with ICG/MSNs. Conclusions ICG/MSNs have good biocompatibility, good PDT effect on pancreatic cancer cells and pancreatic cancer xeno?grafts. Near?infrared fluorescence imaging with ICG/MSNs could delineate the tumor location.