Against the background of global climate change, how to effectively protect the Mcdika plateau wetland is an urgent question that needs to be addressed. To effectively protect the source of Lhasa River, this study used the remote sensing image interpretation method and model evaluation method to analyze the characteristics of change in the landscape pattern of the Mcdika wetland and evaluated changes in its ecosystem services function. The results show that the area of the Mcdika wetland has decreased by 5825 hm², most of which is marsh wetland. Grassland and unused land area have increased by 5727 hm² and 98.5 hm², respectively. Furthermore, the trend of climate warming and drying, indicated by clear increases in temperature and ground temperature over the past 30 years, has led to the shrinking of the wetland area and a significant increase in the area of alpine meadow. The results of ecosystem services function show that the main ecological service function of the Mcdika wetland reserve is regulation, which accounts for 70% of the total. The shrinking of the wetland area is the primary reason for the weakening of the ecological service function of the Mcdika wetland reserve.