The present invention relates to the field of display techniques. Provided are a light source assembly (0), a backlight module (1), and a display device. The light source assembly (0) comprises a light source (01) and a collimator (02) provided at a light exit surface (P) of the light source (01). When emitted from the light source (01) to a preset surface (A) of the collimator (02), light and the light exit surface (P) form a first included angle (J1). When the light exits the preset surface (A), the light and the light exit surface (P) form a second included angle (J2). The first included angle (J1) is smaller than the second included angle (J2). An amount of light entering per unit area of the preset surface (A) is greater than a preset light amount threshold. The light source assembly (0) solves a problem in which an overall utilization rate of a collimator (02) is low, thereby increasing the overall utilization rate the collimator (02). The present invention is applicable to a display device.