Aim To investigate the efficacy of different doses of atorvastatin in the treatment of acute coronary syndrome (ACS) patients with baseline low-level low density lipoprotein. Methods 102 patients with ACS associated with baseline low-level low density lipoprotein were selected from January 2016 to December 2017. The patients were randomly divided into three groups:low-dose short-term group, high-dose short-term group and low-dose long-term group, with 34 cases in each group. Low-dose short-term group and low-dose long-term group were treated with atorvastatin 10 mg/day for 9 months and 12 months respectively, high-dose short-term group was treated with atorvastatin 40 mg/day for 9 months.Automatic biochemical analyzer was used to detect triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDLC) and low density lipoprotein cholesterol (LDLC). The blood lipid levels and the incidence of major adverse cardiovascular and cerebrovascular events of the three groups of patients were compared. Results Before treatment, there were no significant differences in baseline data and 4 indexes of blood lipid among the three groups (P＞0.05).After 3 and 9 months of treatment, the levels of TC, LDLC and TG in the high-dose short-term group were lower than those in the low-dose short-term group and low-dose long-term group, and the levels of HDLC were higher than those in the low-dose short-term group and low-dose long-term group (all P＜0.05). After 12 months of treatment, the efficacy of 4 indexes of blood lipid in the low-dose long-term group was improved better than that in the low-dose short-term group after 9 months of treatment. There was no significant difference in 4 indexes of blood lipid in the low-dose long-term group after 12 months of treatment and high-dose short-term group after 9 months of treatment (P＞0.05). There was no death at the end of the treatment in the three groups. The incidence of major unconscience-related cerebrovascular events in the high-dose short-term group and low-dose long-term group was 11.76%, slightly lower than that in the low-dose short-term group (17.65%), but there was no statistical significance in the three groups (P＞0.05). Conclusion The use of atorvastatin in the treatment of ACS with baseline low-level low density lipoprotein is dose-dependent and time-dependent, so it is recommended to increase the dose and prolong the treatment time.