A dust collection hood installed on a grinding machine tool which includes a driving motor and at least one grinding portion driven by the driving motor to rotate. The dust collection hood includes a circumferential wall surrounding the grinding portion and a dust collection cap. The dust collection cap is coupled with the circumferential wall to form a dust collection chamber to house the grinding portion, and includes a top fastened to the grinding machine tool. The dust collection chamber is formed at a height gradually decreased from the top towards the circumferential wall. The dust collection cap further includes a dust discharge port communicating with the dust collection chamber and an airflow guiding portion to guide airflow from the dust collection chamber to the dust discharge port. Thus a great amount of dust generated during grinding can be discharged via the dust discharge port.