If you ofen talk to a chinese ppl,may be a half of year...But just simple....

If you learned pinyin, doing some simple exercises every day, a month can understand simple sentences.

thanks shevelen8 is it too hard to memorize the words? how much should i practice for that?

as long as you memorize the necessary words from the wordlists

depends on how long you can work on this language. For being able to understand oral chinese, maybe you have to find the suitable tv or radio programms sometimes or even find the right people to talk to, since there are too many dialects around China. Even as a Chinese myself i could not understand some people and conversations from time to time, things gonna be really worse when it comes to core issues, people from the same region are more likely to talk in dialects and people from other places elsewhere in china cant get what they said... For being actually able to understand basic Mandarin ,i guess maybe at least one year...