Background The current treatment program with penehyclidine hydrochloride (PHC) for acute severe organophosphorus pesticide poisoning (ASOPP) patients exerts a positive effect but with concerned adverse reactions. Objective To evaluate the treatment effect of a revised ASOPP treatment program with PHC. Methods A prospective single-blind randomized controlled trial was conducted. A total of 157 patients with ASOPP were divided into a revised treatment group (82 cases) and a conventional treatment group (75 cases) by random number table. The two groups received the same basic treatment measures including active life support, routine gastric lavage, catharsis, and pralidoxime treatment. The revised treatment group followed a revised PHC treatment protocol initiated by first a small dose of PHC and followed by small doses of PHC administration/discontinuation through frequent observations at different time points. The conventional treatment group received the conventional program. Treatment effects and incidence rates of possible adverse reactions were compared between the two groups. Results Compared with the conventional treatment group, the revised treatment group obtained delay in penetrogenation time point, higher success rate in catharsis, earlier cholinesterase-turning time, and shorter hospitalization period with statistical significance (all Ps＜0.05). No differences were found in terms of time for symptoms of poisoning to disappear, incidence rates of intermediate myasthenic syndrome and delayed polyneuropathy, mechanical ventilation time, and cure rate (all Ps＞0.05). Less adverse reactions occurred in the revised treatment group including tachycardia and delirium than in the conventional treatment control group (all Ps＜0.05). Conclusion The revised ASOPP treatment program with PHC is similar to the current recommended treatment program in treatment effects, but with less adverse reactions.