The invention relates to a double-side etching high-temperature and high-pressure printed circuit board heat exchanger. The double-side etching high-temperature and high-pressure printed circuit board heat exchanger is composed of a heat exchanging core, a flow equalizing section, a hot fluid inlet and outlet port and a cold fluid inlet and outlet port. The core is divided into an inlet section, a core heat exchanging section and an outlet section. According to the heat exchanger, runners are machined in the double sides of heat exchanging plates with a certain thickness in a photochemistry manner, a laser etching manner, a machining manner and the like. The first heat exchanging plate and the second heat exchanging plate are arranged in a spaced manner. A fusion type channel novel structure is adopted in an inlet distribution section, and fluid in the heat exchanger can be easily distributed more evenly. The heat exchanging efficiency of the heat exchanger can be improved, the thermal stress damage at an existing channel sharp corner is effectively avoided, the circulation section area of the heat exchanger is increased, and the compactness of the heat exchanger is improved; thermal stress distribution at the sharp corner is improved, plastic deformation caused by stress concentration is avoided, and the even distribution of fluid in the heat exchanger is improved; and the safety performance of the heat exchanger is improved, and the service life of the heat exchanger is prolonged.