Background and Purpose: This study aimed to investigate the effects of different types and frequencies of physiotherapy on the ventilator weaning among patients in the intensive care unit (ICU) and to identify the optimal type and frequency of intervention. Methods: Randomized controlled trials (RCT) provided the dosage of ICU rehabilitation were searched in PubMed, Cochrane Library, Embase, and Airiti Library. The treatment types were categorized into passive, neuromuscular electrical stimulation (NEMS), progressive mobility, and multi-component. The frequencies were divided into high (≥ 2 sessions/day or NEMS of > 60 minutes/day), moderate (1 session/day, 3-7 days/week or NEMS of 30-60 minutes/day), and low (1 session/day, < 3 days/week, or NEMS of < 30 minutes/day). The outcomes were the parameters related to ventilator weaning. Results: Twenty-four RCTs were recruited for systematic review and 9 out of 24 articles with passive treatment as control were analyzed in meta-analysis. Early rehabilitation significantly increased the extubation rate and reduced the ventilator duration of patients in the ICU, especially progressive mobility included out-of-bed exercises had an optimal treatment effect (SMD = 1.12; 95% CI = 0.27-1.98). Compared to usual care or low-frequency intervention, high-frequency intervention increased the extubation rate (OR = 3.93; 95% CI = 2.17-7.11) and moderate-frequency intervention reduced ventilator duration (SMD = 0.31; 95% CI = 0.06-0.57). Conclusions: For patients in ICU, an early rehabilitation with progressive mobility protocol and a high frequency of chest physiotherapy more than 2 treatments per day have better effects on the ventilator weaning. Clinical Relevance: The study results may serve as an empirical basis for devising intervention plans when there is insufficient medical manpower to develop early rehabilitation in clinical units.