How could Marco polo visit China if the foreign travel is banned during that time in China?

When exactly do you think Marco Polo explored a land route to Asia from Europe? He lived during the late 1200's and early 1300's. I don't believe China had a foreign travel ban. They probably welcomed the economy boost the Spice Trade and European exploration brought.

Marco Polo travelled along what was called, 'the Silk Road', a road that was used (and open to anybody), for centuries as a trade route.

I dont think he reach china that time, may be just the border of china

generally speaking, foreigners are banned from China, but there are some exceptions.

a good travel agent.

The Chinese never banned foreigners from visiting China. They did ban - at various times - foreigners from carrying on business or religious teaching, or access to certain areas within China. This was more a case of local regulations in response to foreign 'misbehaviour' or wars going on in various territories. They also banned the removal of certain technologies (notably silk-worm farming). Generally China welcomed foreign traders and diplomats if they were prepared to conform with (or not directly challenge) the Chinese view of their own superiority. If you are talking about 'total' seclusion then you might be thinking of Japan which had a complete ban on foreign contact (the Sakoku policy) between 1641 and 1853. If Marco Polo visited China he would have been one of thousands doing so at that time. Most would have visited trading ports, or cities along the Silk Road. I suspect that Marco Polo 'romanced' the story of his travels (I believe the modern expression would be 'sexed up') in order to make a more sale-able book. In doing so he cast doubt on the 'truth' of everything he claims to have done. What is indisputable is that Christopher Columbus (and others) were inspired by Marco Polo's tales of the wealth of the East.

Funny thing about that. Marco Polo probably never made it to China. It's been suggested that he made it to Persia or possibly even the most western part of modern China, which were both part of the Mongolian Empire at the time (technically, China didn't even exist when Marco Polo supposedly went there). The Mongolian empire opened communication and travel between China and the west and he most likely heard about China from them. (It's also this area that invented noodles as well, not China). Marco Polo most likely made the rest up based on stories that he heard. The best support to Marco Polo never making it to China comes from the fact that the Chinese have been meticulous record keepers for the past 2000 years and Marco Polo, who claimed to have beena governor, is never mentioned.