The invention relates to the field of automobile steel plate spring suspension systems, in particular to a leaf spring fixed-end bracket assembly and an assembly method thereof. The leaf spring fixed-end bracket assembly comprises a leaf spring, a fixed-end bracket, a pin shaft, a fastener and a grease nipple. The pin shaft is provided with an oil channel in the axial direction, an outer side pinhole seat of the fixed-end bracket is provided with an outer side pin hole, an inner side pin hole seat is provided with an inner side pin hole, the fixed end of the leaf spring is bent inwards to form a rolled lug, the pin shaft penetrates into the outer side pin hole, the rolled lug and the inner side pin hole, the outer side end of the pin shaft and the outer side pin hole are fixed, the innerside pin hole is a counter bore, the minimum hole diameter of the inner side pin hole is greater than the outer diameter of the inner side end of the pin shaft, the outer wall of the fastener is provided with the outer side wall matched with the inner side pin hole, the inner wall of the fastener is connected with the inner side end of the pin shaft through threads, the fastener is internally provided with a channel communicating with an oil way, and the grease nipple is placed in the channel. By means of the leaf spring fixed-end bracket assembly and the assembly method, fast and accurate installation of the fixed end of the leaf spring can be realized.