[Objectives]  To investigate the effect of releasing a pheromone (Bee activity enhancer) to overcome the effects of adverse weather conditions on the pollination efficiency of Osmia excavata Alfken, one of the most important pollinators in northern China. [Methods]  We compared O. excavata activity levels, fruit set and fruit yield at sites where the pheromone was released to that at sites where it was not released. [Results]  The dependence of apples on O. excavata for pollination was 0.95. The flower-visiting efficiency of bees in pheromone treated orchards was 1.34 times higher than in control orchards, and releasing pheromone significantly increased the fruit set of apples. Releasing pheromone also increased mean apple weight by 3.53 g, and improved fruit quality by increasing the content of vitamin C by about 0.15 mg/100 g. [Conclusion]  Releasing pheromone in apple orchards can counteract the adverse effects of low temperature by increasing the frequency at which O. excavata visits flowers, thereby improving fruit quality, raising fruit yield and reducing fruit loss.