Objective: The purpose of this study was to analyze the effect of hyperglycemia on the prognosis of patients with alteplase (rt-PA) in acute ischemic stroke (AIS) patients, so as to provide relevant evidence for clinical treatment. Methods: The data of 256 patients with acute ischemic stroke who underwent rt-PA intravenous thrombolysis in Funan people’s Hospital from January 2018 to December 2019 were collected retrospectively. Patients were divided into normal glucose group (glucose ≤7.8 mmol/L) and acute hyperglycemia group (glucose >7.8 mmol/L) based on the admission blood glucose, and patients were divided into normal HbA1c group (HbA1c ≤6.5%) and chronic hyperglycemia group (HbA1c >6.5%) based on HbA1c level. The patients’ age, gender, past medical history, biochemical indexes, NIH Stroke Scale (NIHSS) score, clinical prognosis and other indicators were analyzed. Results: Acute hyperglycemia, chronic hyperglycemia at admission, and previous history of diabetes were all associated with poor prognosis after thrombolysis. On admission, compared to patients with normal blood glucose, the NIHSS scores (P=0.039) and 24 h NIHSS scores (P=0.025) were lower, and the rates of poor prognosis (P<0.05) was higher in patients with acute hyperglycemia. There was no significant difference in NIHSS scores before and after thrombolysis in patients with chronic hyperglycemia, but the incidence of adverse events was higher (P=0.043). Logistic regression analysis showed that the history of acute hyperglycemia, chronic hyperglycemia and diabetes mellitus were independently related to the poor clinical prognosis of patients with acute cerebral infarction after intravenous thrombolysis. Conclusion: For AIS patients with rt-PA intravenous thrombolysis, the incidence of adverse events after thrombolysis was increased in case of pre-thrombolysis blood glucose >7.8 mmol/L or HbA1c >6.5% and previous diabetes history. Although hyperglycemia affects the prognosis of thrombolytic therapy, thrombolysis can still improve the neurological function defect of patients with hyperglycemia and AIS in general. Whether correcting acute hyperglycemia improves the outcome of rt-PA thrombolytic therapy in AIS patients still needs to be confirmed by a large prospective multicentre randomized controlled trial.