Abstract: In order to accurately and objectively assess the human health risks of mercury-contaminated sites and overcome the shortcomings of current soil control values that are too conservative, this study conducted a detailed environmental investigation on a large mercury chemical waste site in northeast China. Monte Carlo probabilistic simulations were performed for total mercury data from 313 soil samples (sampled at a depth of 0.5 m), zero-valent mercury content data from 9 soil samples and gastrointestinal availability data for mercury from 30 soil samples at the site. Probabilistic predictions of human health risks and remediation target values for oral ingestion and gaseous inhalation at the site were made using the parameter probabilistic simulation values. The results show that: (1) The total mercury content of the site varied spatially from 0.002 to 579.14 mg/kg with a variable coefficient of 3.88 and was mainly concentrated in the 0-2.5 m. The average content of zero-valent mercury was 15.2%±6.4%, showing a significant negative logarithmic relationship with the total mercury concentration (R²=0.7845). The average content of gastrointestinal administrable mercury was 2.74%±2.81%, which was not significant correlated with the total mercury. (2) Inhaled gas was the main source of human health risks at the site, accounting for 90% of the total risk value, with a 5% probability of non-negligible (risk quotient >1). The oral intake route had a 0.15% probability of non-negligible (risk quotient >1). (3) The combined risk control remediation target value based on zero-valent mercury and gastrointestinal bioavailable mercury content was 53.8 mg/kg (5% quantile), with a corresponding remediation area of 5, 427.9 m², which was significantly lower than the remediation area (37, 057.6 m²) determined using the risk screening value (8 mg/kg) of Soil Environment Quality Risk Control Standard for Soil Contamination of Development Land (GB 36600-2018) as the remediation target value for the construction site category 1 site. The proportion of zero-valent mercury and the weight of children were the most important parameters affecting the remediation target values, contributing -78% and 42% to the uncertainty of the remediation target values, respectively. The research showed that the probability risk assessment based on mercury species and bioaccessibility can more accurately assess the risks and main risk pathways of contaminated sites, and can also effectively lower the corresponding restoration target values and avoid over remediation.