Early morning off (EMO) is a common feature of Parkinson's disease (PD). This study aimed to characterize its clinical features and develop a convenient and pragmatic self-assessment instrument in a Chinese nationwide population. This study was conducted on 942 PD patients admitted to 55 clinic centers for movement disorders between June 2018 and May 2019 in China. Stepwise logistic regression analyses were performed to determine potential risk factors and the most predictive symptoms of EMO, as well as whether EMO was an independent risk factor of functional dependency in daily life. Based on this, a 7-question scale was derived for EMO screening. Diagnostic accuracy of this scale was assessed from the area under the receiver operative characteristic curve (AUROC) and its 95% confidence intervals (CIs). We further calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the optimal cutoff point. EMO occurred in 49.2% of PD patients across all disease stages. We identified 7 symptoms most predictive of EMO, including bradykinesia or rigidity, excessive sweating or salivation, difficulty in turning on or getting out of bed, muscle cramp, fatigue or sleepiness, frozen state or freezing gait, and tremor. The resulting 7-item scale was confirmed to be of good discrimination with a relatively large AUROC of 0.83, a relatively high sensitivity of 75.7%, specificity of 77.5%, PPV of 76.5%, and NPV of 76.7%. Nonideal nighttime sleep, long PD duration, advanced H&Y stages, posture instability gait difficulty-dominant or mixed subtypes, and high levodopa dose were independently associated with increased risk of EMO. EMO patients were at 87% higher (OR = 1.87, 95%CI: 1.07-3.32) risk of experiencing functional dependency in daily living compared with their counterparts. We demonstrated that EMO is a common feature for PD patients across all disease stages and put forward an EMO-specific screening card of sufficient accuracy and brevity. Meanwhile we have thrown some light upon potential determinants and negative health effects of EMO. Our findings may exert great impact on improving the awareness, recognition and management of EMO in PD patients.