The invention provides a heat treatment process for surface hardening and carbonitriding of hydraulic parts, which includes the following steps: a washing the hydraulic parts preparing for heat treatment to remove greasy dirt; b warming a carburizing multi-purpose furnace, and performing pre-carburizing treatment; c putting the hydraulic parts washed cleanly through the step a in the carburizing multi-purpose furnace, and performing strong carburizing; d adjusting carbon potential after the strong carburizing to perform diffusion; e putting the hydraulic parts after carbonitriding in the stepd in a quenching chamber of the carburizing multi-purpose furnace to be quenched, filtering oil and discharging from the furnace; and f washing the hydraulic parts of the step e, and putting the hydraulic parts in a tempering furnace to be tempered to obtain products.