Abstract： The key problem for fast first order reliability method (FORM) is to quickly find out the design point of limit state function. After analyzing some HLRFbased design point searching algorithms, a novel FORM was proposed based on the Shi-Shen line search rule. As this FORM is based on adaptive step size parameters, it is referred to as aHLRF. Compared with the traditional HLRF-based method, the aHLRF not only is globally convergent, but also can adaptively estimate some important algorithm parameters using previous iteration information. The robustness and efficiency of the aHLRF were also discussed. Examples illustrate that the aHLRF is very efficiency for estimating the first order reliability probability, especially for problems whose the nonlinearity of limit state function near the design point is very large.