When reciting, the voice is stiff, rough and not round, the speed and intonation have not changed, and the emotional color is not very good. What should I do?

I suggest you practice more at home at ordinary times, and diligence can make up for it. In particular, you can consult a Chinese teacher, ask for more skills or pronunciation methods, or watch more news broadcasts or listen to some radio programs. Those hosts have done a good job in this respect and are good learning objects. Learn to speak in front of the mirror and learn to recite. Some reasons for stiff voice are stage fright. Try to find more opportunities for yourself to recite in front of everyone. You may not be used to it at first, but stick to it slowly and it will be effective.