What is the best time to make this tour (Trekking Tour Across China)?

The best travel time for Trekking Tour Across China (Shanghai Guilin Zhangjiajie Xi'an Beijing) is in spring (April May) and autumn (September October), when the climate is pleasant and the scenery is stunning (such as Shanghai cherry blossoms, Guilin Li River, Zhangjiajie clouds and mist, Xi'an historical sites, Beijing red leaves), and it can avoid high temperatures and heavy rain in summer, cold winters, and peak holiday crowds, making the journey comfortable and smooth.