Sorry can't type chinese. Just finished reading Quiet, a book about introverts. Basically, people are different, and the first thing a parent can do is to understand and accept the child as he/she is. It is natural that some people prefer to be alone and play on their own. It might be helpful if you read the book, especially the related chapter. Is your son happy by himself? Or is he upset not being able to play with others? That makes a difference. If he is happy, you might want to encourage him to try playing with others every now and then, but let him decide which style he prefers. If it was the later, then you need to help him figure out how to play along with others.
One practical suggestion is to set up play dates with kids of similar age, especially kids from the daycare, preferably one-on-one, to help your son getting used to play with others and build up friendship with other kids.
ps，和天生性格也有关，我小时候就很内向，也走过很多很多弯路。直到高二和大三之间才真正养成一些有益于人际交往的性格。对于自己的孩子，真希望可以正确引导，让他少走一些弯路……谢谢！
Is your son happy by himself? Or is he upset not being able to play with others? That makes a difference. If he is happy, you might want to encourage him to try playing with others every now and then, but let him decide which style he prefers. If it was the later, then you need to help him figure out how to play along with others.
One practical suggestion is to set up play dates with kids of similar age, especially kids from the daycare, preferably one-on-one, to help your son getting used to play with others and build up friendship with other kids.