The invention relates to a 1.3-centimeter-waveband dual-polarized refrigeration receiver dewar used for observing molecular spectra lines, pulsar and VLBI (very long baseline interferometry) in the radio astronomy. The receiver dewar consists of a dewar cavity, a shielding cover, a microwave window, a frame carrier, a support, a ring-shaped fixing frame, a soft connector, a feed source, a transition waveguide, a circle and square converter, a polarizer, a low-noise amplifier, a waveguide coaxial converter, an isolator, a semi-rigid coaxial cable, a microwave window sealing film, a microwave window fastening ring, an air-filled cavity, an air-filled cavity sealing film, an air-filled cavity fastening ring, an air cylinder and a refrigerator. The 1.3-centimeter-waveband dual-polarized refrigeration receiver dewar with high sensitivity has the advantages that the design scheme is more reasonable, good sealing performance is ensured, internal devices can be well fixed and supported, the refrigeration effect is more excellent, the stability is better, the sensitivity is higher, and the thermal radiation can be effectively isolated, thereby being capable of being better applied to high frequence radiation characteristic study of molecular spectra lines and pulsar and radio astronomy observation of VLBI.