This dataset is recorded by 26 subjects in Shandong Provincial Hospital using wearable ECG devices. It totally includes 208 segments with a duration of 30 seconds. The sampling rate is 256Hz. All the data format is ‘.mat’. This dataset can be used for signal quality assessment as the unacceptable category. All the data are recorded in free-living conditions with various noises. This dataset is recorded by 26 subjects in Shandong Provincial Hospital using wearable ECG devices. It totally includes 208 segments with a duration of 30 seconds. The sampling rate is 256Hz.