The invention discloses a pair of trousers having a knee protecting function and a making process of the trousers. The pair of trousers comprises an upper front sheet and a lower front sheet, whereinthe lower front sheet comprises a left lower front sheet and a right lower front sheet; the upper front sheet comprises a bottom edge dividing line, a left side stitch and a right side stitch; the bottom edge dividing line is composed of a left lower bottom edge dividing line and a right lower bottom edge dividing line; the left lower front sheet and the right lower front sheet comprise top edge dividing lines, inner dividing lines and outer side stitches; the top edge dividing lines of the left lower front sheet and the right lower front sheet are perpendicular to the corresponding inner dividing lines and the outer side stitches; the top edge dividing line of the left lower front sheet is connected to the left lower bottom edge dividing line of the upper front sheet in an overlapped mode; the top edge dividing line of the right lower front sheet is connected to the right lower bottom edge dividing line of the upper front sheet in an overlapped mode; the inner dividing line of the left lower front sheet is connected to the inner dividing line of the right lower front sheet in an overlapped mode; and an intersection point of the left lower bottom edge dividing line and the right lower bottom edge dividing line corresponds to the vertex of a knee of a human body. With the application of the trousers provided by the invention, effects of knee protecting and keeping knees warm canbe achieved; and the pair of trousers is convenient to take off and take on and is suitable for wearing outside.