We report a 40 Gb/s burst mode optical clock recovery (BM-OCR) by injection locking a dynamically switched quantum dash mode-locked laser diode. We investigated in detail the performance of the BM-OCR operation after 52 km transmission. High quality BM-OCR after transmission is achieved with a locking time of ~25 ns, and 40 GHz recovered packet clock with 46 dB signal to noise floor suppression and 64 fs timing jitter (100 Hz to 1 MHz). The reported BM-OCR has a continuous tuning wavelength range from 1535 to 1560 nm, power dynamic range of no less than 6.7 dB. The frequency deviation tolerance of the BM-OCR is within -427 to +226 ppm at 39.813 Gb/s (OC-768 standard line rate), which is compliant with the specifications in the IEEE 40/100-Gb/s Ethernet standard. These results indicate the promising future applications of the proposed BM-OCR in high speed burst mode optical receiver.