In this work, a wearable instrumented smart clothes with an accelerometer sensor embedded on the upper abdomen close to the diaphragm was used to detect respiration of subjects. A detection algorithm was proposed and verified with 30 testing cases on male and female subjects separately. More than 97% of accuracy is achieved by comparing with the detection results from respiratory belt conducted simultaneously. This clothes and respiratory detection is extremely useful to monitor human's respiration when the subjects are in sleep and hence could be used for the detection of sleep apnea syndrome.