The invention discloses a lower profile of a sliding window. The lower profile comprises a mold cavity and a glass clamping groove, wherein the glass clamping groove is arranged at the upper part of the outer side of the mold cavity; the mold cavity is a quadrangle with an opening in the lower part; the mold cavity comprises a left vertical baffle, a right vertical baffle, a left diversion trench, a right diversion trench and a transverse plate; the left vertical baffle is connected with the right vertical baffle; the left diversion trench is connected with the left vertical baffle; the right diversion trench is connected with the right vertical baffle. As the sealing strip is arranged on the inner side of the glass clamping groove, a good sealing property is ensured when glass is embedded into the glass clamping groove, and due to the groove opening design, sealing combination of the lower profile and a lower slide profile is improved.