A two-level compress low temp heat pump system suitable for cold areas is formed after adding a high pressure level unit composed of a high pressure level compressor, a high pressure level unit composed of a high pressure level compressor, a high pressure level four-port valve, mid cut-off thermal power expanding valve, electro-magentic valve, mid cool and cold-production medium connecting pipe to ordinary heat pump system cold-producing medium circuit consisting of compressor, four-port valve, cold-producing medium/air heat exchanger, thermal power expanding valve, one-way valve, high pressure reservior, dry filter, cold-producing medium/water heat exchanger and/or cold-producing medium/air heat exchanger, gas/liquid separator, pump and/or fan and water channel connecting pipes, which can operate under-18 deg.c. |