Terahertz waves play an increasingly important role in the areas about astronomical exploration and imaging due to its unique atmosphere sensitivity and space transmission property. In order to realize high sensitive terahertz detection, we develop mesa-type silicon-based blocked-impurity-band (BIB) terahertz detectors. For further verify the influence of device structure parameters on the performance of the BIB detectors, the different doping concentration of absorption layer was fabricated. Moreover, the influence of various doping conditions on the performance of BIB terahertz detector were analyzed. Then the blackbody responsivity and response spectral performance were measured at 4K liquid helium cryogen temperatures. The results show the blackbody responsivity is proportional to the doping concentration of the absorption layer within a range. When the doping concentration increase to a certain degree, the bandgap narrowing effect will become obvious, which results to the impurity band and bottom of the conduction band degeneracy and the function of the device will be invalid. According to the measurement results, when the doping concentration of the absorption layer is 7*1016cm-3, the BIB terahertz detector we fabricated has the optimal blackbody responsivity and response spectral performance, and its peak responsivity can reach 15.4A/W. As a further step, the focal plane arrays mesa-type silicon-based BIB terahertz detectors will be designed.