In this study, self-supporting zeolite NaP was synthesized from fly ash-based geopolymer via in-situ hydrothermal method. The effects of various factors, such as hydrothermal temperature, crystallization time, concentration and volume of sodium hydroxide (NaOH), on the crystallinity, morphology and mechanical strength of the resulting products were investigated. Optimal conditions for the synthesis of zeolite NaP from fly ash-based geopolymer were determined to be as follows:temperature 100℃, curing time 24 h in the 50 mL of 2.0 mol/L NaOH solution. The compress strength of zeolite NaP is 23.21 MPa with specific surface area of 50.46 m²/g, which can meet the industrial manufacturing and production standards. The in-situ hydrothermal method is a facile, environment-friendly and controllable method for the preparation of self-supporting zeolite. Moreover, different types of zeolites can be synthesized by controlling the raw material compositions and reaction conditions.