Objectives: To investigate whether postnatal benzo(a)pyrene (B(a)P) exposure caused the impairments on the process of neurodevelopment and the alteration in the calcium medium in the neonatal rats. Material and Methods: Eighty neonatal Sprague Dawley (SD) rats were randomly divided into 5 groups (untreated control group, vehicle group, 0.02 mg/kg, 0.2 mg/kg and 2 mg/kg B(a)P-exposed group). Rats were treated with B(a)P by the intragastric administration from postnatal day (PND) 4 to 25. Morris water maze (MWM) was employed to observe the spatial memory of rats. The activity of calcium adenosine triphosphatase (Ca²⁺-ATPase), sodium-potassium adenosine triphosphatase (Na⁺-K⁺-ATPase) and calcium-magnesium adenosine triphosphatase (Ca²⁺-Mg²⁺-ATPase) in the hippocampus were detected by commercial kits. Fura-2 pentakis(acetoxymethyl) (Fura-2/AM) probe and reactive oxygen species (ROS) reagent kit were used for measuring the concentration of Ca²⁺ and ROS in the hippocampus synapse, respectively. Results: Rats exposed to B(a)P resulted in the deficits in the spatial memory manifested by the increased escape latency and decreased number of crossing platform and time spent in target quadrant in comparison with the control groups. Benzo(a)pyrene exposure caused the significant decrease in the ATPase activity in the hippocampus and caused Ca²⁺ overload in the synaptic, besides, the ROS concentration increased significantly which may further induce neurobehavioral impairment of the neonatal rats. Conclusions: Our findings suggest that postnatal B(a)P exposure may cause the neurobehavioral impairments in the neonatal rats, which were mediated by the decreased ATPase activity and elevated Ca²⁺ concentration. Int J Occup Med Environ Health 2017;30(2):203–211