Grating-coupled external cavity diode lasers play an important role in cold atoms physics research and other fields. In this paper, combined with the application requirements in the interference process of 87Rb atom interferometer, the tuning and frequence-locking characteristics of a self-made compact 100 kHz external cavity diode laser seed coupled with volume Bragg grating(VBG) are chiefly studied with the optical phase locked loop. The measured coefficients of frequency-current and frequency-temperature are 400 MHz/mA and 16 GHz/℃, respectively. Laser frequency locking of the 100 kHz diode seed is demonstrated, and the frequency fluctuation of the locked seed is less than 500 kHz(peak to peak) within a 10 s measurement, and the power fluctuation of 12 hours is better than 0.1%(rms), which can meet the application requirements of all physical processes of the cold atoms interferometer, especially in the interference process.