The invention discloses a system and method for concentration detection and training based on functional near infrared spectrum technologies. The system comprises a wearable fNIR sensing device and an intelligent terminal; a fNIR control module in the wearable fNIR sensing device controls switching-on, switching-off and spectral wavelength of a signal emission source in a fNIR signal emission module, switching-on and switching-off of a sensor in a fNIR signal collection module as well as opening and closing of signal channels, and near infrared spectrum signals on each signal channel under different spectrum lengths are collected cyclically and transmitted to the intelligent terminal; and the terminal equipment uses a built-in concentration analysis module to transform the near infrared spectrum signals into hemoglobin content information in real time and then quantify the information into a concentration index.