OBJECTIVE： To investigate the possibility of constructing anti-cancer drug in-situ hydrogel with self-assembling peptide RAD16-Ⅰ. METHODS： The rheological parameters as storage modulus （G′ ）， loss modulus （G″ ） and phase angle （Δ） of 0.1％， 0.2％ and 0.5％ RAD16-Ⅰ solution containing paclitaxel or not were determined by rheometer before and after mixing with isometric phosphate buffer solution （PBS）； RAD16-Ⅰ solution containing paclitaxel or not were mixed with breast cancer MDA-MB-435S cells culture medium to obtain hydrogel， the status and effect of which on cell morphology were observed by inverted microscope （compared with paclitaxel solution）. RESULTS： In RAD16-Ⅰ solution containing paclitaxel or not， G′  was close to or slightly higher than G″ ， and G′  and G″  had changed slightly as the concentration of peptide increased. Compared with not mixed with PBS， G′  increased significantly in concentration-dependent manner after mixed with PBS， and G″  also increased but was slighter than G′ ； Δ decreased significantly. In cell culture media， RAD16-Ⅰ solutions containing paclitaxel could form hydrogel and maintain their gel form， cancer cells kept same morphology after treated with hydrogel and same concentration of paclitaxel solution for same time. CONCLUSIONS： RAD16-Ⅰ solutions containing paclitaxel can form hydrogel under simulated physiological conditions， which can maintain their gel form and have anti-cancer effect of paclitaxel.