The Hypoaspis aculeifer Raumilben is a polyphagous species which has an important role in control of insects, mites, nematodes and fungus in the soil habitats and also is used as a biological control agent in greenhouses and fields. In this paper, the effects of constant temperature on the demography of H. aculeifer fed on Rhizoglyphus echinopus have been investigated. This study was done at eight constant temperatures (16, 17.5, 20, 22.5, 25, 27.5, 30, 32.5) oC, 60±5% RH and photoperiod of 16:8 (L: D). Net reproductive rate (R0) of the predacious mite was 0.91, 14.67, 21.87, 24.87 and 32.38 ♀/♀/G at 16, 20, 22.5, 27.5 and 30oC respectively. The intrinsic rate of increase (rm) values ranged from -0.002 (16oC) to 0.252 (30oC) d-1. The finite rate of increase (l) was 0.997 d-1 at 16oC, and 1.286 d-1 at 30oC. Using the linear model (Ikemoto and Takai), the low temperature threshold of H. aculeifer estimated for pre-adult stages and also for constant temperature were 10.8oC and 169.3 degree days for females and 11.2oC and 163.9 degree days for males. The estimations of the optimum temperature, low threshold and high threshold of development were estimated by chosen models (Analytis (1) / Allahyari, Analytis (2), Analytis (3), Analytis (1)).