A process for preparation of gabapentin hydrochloride by converting 1,5-dicyano-2,4-dioxo-3-azaspiro[5,5]-undecane into 1,5-diaminoformyl-2,4-dioxo-3-azaspiro[5,5]-undecane at a temperature of 65.degree. C. to 85.degree. C. in the presence of a strong acid, and then carrying out Hofmann rearrangement under an alkaline condition. The starting material of the process is readily available. The process is simple, and can reduce the purification procedure of intermediates, reduce production cost, and obtain product with higher purity.