Both "grand plan" and "grand plan" are correct, but their meanings are slightly different. "Grand plan" refers to a grand plan or grand strategy, which is often used to describe the grand goals and development plans of a country, an organization or an individual. For example, "The great cause of the country needs the concerted efforts of everyone in Qi Xin." "Grand Plan" emphasizes the meaning of atlas and blueprint, and is often used to express detailed plans, designs or charts. For example, "he made a detailed grand plan for the company to guide the future development."