A new compatibilized method was used to prepare thermoplastic elastomer (TPE) of nitrile rubber (NBR) and polypropylene (PP) with excellent mechanical properties by dynamic vulcanization. Glycidyl methacrylate (GMA) grafted PP/amino-compound was used as a compatibilizer. The effects of the curing systems, compatibilizer, PP type, and reprocessing on the mechanical properties of NBR/PP thermoplastic elastomers were investigated in detail. Experimental results showed that the addition of amino-compound in the compatibilzer can significantly increase the mechanical properties of the NBR/PP thermoplastic elastomer. Compared with other amino-compounds, diethylenetriamine (DETA) has the best effect. PP with higher molecular weight is more suitable for preparing NBR/PP thermoplastic elastomer with high tensile strength and high elongation at break.