The invention provides a method and an apparatus for determining a windward area of a power transmission tower. The method comprises a section division step of dividing the power transmission tower into a plurality of tower sections, a rod part windward area coefficient determination step of judging whether each rod part in each tower section bears a windward load or not and is a public rod part or not and determining windward area coefficients of all rod parts in each tower section according to a judgment result, a tower section windward area determination step of determining an actual windward area of each tower section according to the windward area coefficients of all the rod parts in each tower section and theoretical windward areas of all the rod parts, and a power transmission tower windward area determination step of determining a windward area of the power transmission tower according to the actual windward area of each tower section, wherein the public rod part is a rod part which bears the windward load in at least two tower sections. According to the method and apparatus, the calculation is accurate and reliable, the repeated calculation of the windward area is avoided, the deviation of windward area calculation is greatly reduced, and the calculation precision of a wind load stress of the power transmission tower is improved, so that the safety of the power transmission tower is ensured.