Objective To explore the severity of hyperhomocysteinemia（ HHcy） among latelife schizophrenia（ LLS） and to analyze its risk factors. Methods A retrospective study was conducted on 380 LLS and HHcy who were hospitalized at Nanjing Youan Hospital from January 1， 2024 to January 1， 2025. Demographic data， past medical history， medication， biochemical tests， and scale scores were collected by reviewing patient case records. Patients were categorized into three groups based on HHcy severity： mild group （Hcy10-＜15 μmol/L， n=156）， moderate group（ Hcy15-≤30 μmol/L， n=167）， and severe group（ Hcy＞30 μmol/L， n=57）. Univariate analysis was performed to analyze the general information of the three groups of patients. The variables with statistically significant differences（ P＜0.05） and variance inflation factor ＜5 in univariate analysis were included in the multivariate Logistic regression model to further analyze the risk factors influencing the severity of HHcy in elderly patients with schizophrenia. Results Univariate analysis revealed statistically significant differences among the three groups of patients in age， gender， weight， body mass index， triglycerides， total cholesterol， apolipoprotein B， uric acid， and cystatin C（ all P＜0.05）. Multivariate Logistic regression analysis showed that， using mild group as a reference increasing age［ OR=1.04， 95%CI（ 1.00， 1.09）， P＜0.05］， increased body mass index［ OR=1.18， 95%CI（ 1.10， 1.27）， P＜0.01］， elevated total cholesterol ［OR=1.47， 95%CI（ 1.10， 1.95）， P＜0.01］， elevated cystatin C［ OR=6.37， 95%CI（ 2.00， 20.27）， P＜0.01］ were risk factors for progression from mild to moderate severity， while female sex［ OR=0.54， 95%CI（ 0.32， 0.93）， P＜ 0.05］ was a protective factor. While using moderate group as a reference， Elevated total cholesterol ［OR=5.99， 95%CI（ 3.53， 10.18）， P ＜ 0.01］ and elevated cystatin C［ OR=14.30， 95%CI（ 2.44， 83.76）， P＜0.01］ were risk factors for moderate to severe progression， while female sex［ OR=0.24， 95%CI（ 0.09， 0.67）， P ＜ 0.01］ was a protective factor. Conclusions This study indicates that LLS exhibit a high prevalence of HHcy， with its severity influenced by multiple factors. Male gender， advanced age， elevated body mass index， total cholesterol， and cystatin C are independent risk factors， and the impact of total cholesterol intensifies with increasing disease severity.