The invention relates to a preparation method of POSS-PEG (Polyhedral Oligomeric Silsesquioxane-Polyethylene Glycol) hybrid hydrogel. The preparation method comprises the following steps: carrying out Michael addition reaction on 4-arm-PEG-MAL and POSS-SH to obtain a POSS-PEG pre-polymer; taking a matrix metalloproteinase substrate peptide as a cross-linking agent, carrying out the Michael addition reaction on the matrix metalloproteinase substrate peptide and the POSS-PEG pre-polymer and crossly linking to form gel, so as to obtain the POSS-PEG hybrid hydrogel. The POSS-PEG hybrid hydrogel provided by the invention has good mechanical strength and the mechanical strength of the POSS-PEG hybrid hydrogel can be finely regulated and controlled through changing the molecular weight of the 4-arm-PEG-MAL and the mol ratio of the POSS-SH to the 4-arm-PEG-MAL; meanwhile, the POSS-PEG hybrid hydrogel can be prepared in a triethanolamine with low concentration and gel formation time is short; the damages or loss on seed cells or medicines loaded on the POSS-PEG hybrid hydrogel can be reduced as much as possible under the condition that basic physicochemical properties are ensured.