The utility model discloses a cavity absorber based on linear fei nieer solar collector, cavity in casing, casing, the heat absorption pipe that is located the cavity and the glass of cap seal cavity lap, the casing is semi - cylindrical, and the casing includes shell and inner wall, and it has the heat preservation to fill between shell and the inner wall, the cavity be semi -cylindrical, heat absorption pipe be many more than two, many heat absorption pipes all attached on the inner wall, many endothermic pipes are the straight tube of following the cavity axial and setting up, and many heat absorptions are managed the constitution of establishing ties mutually in proper order and are curved circuitous book shape heat exchanger tube bundles, this heat exchanger tube bundles and inner wall constitution pipe wing formula heat transfer structure. The pipe wing formula heat transfer structure that this cavity absorber adopted semi -cylindrical cavity and heat exchanger tube bundles and inner wall to constitute can let the solar radiation heat distribution after focusing on even, prevents absorber local overheat to absorptive heat can be absorbed by the working medium that flows effectively.