Dear phan tuan son!
in the message ("below the link is given"), you have admitted that "Myself don't understand this code".

http://www.8052.com/forum/read.phtml?id=52658

it means that you do,t know that in which line of C program it has been declared that you have to connect lcd pins with this port,
in the assembly program ("you have written from the tutorial"), the lcd data bits are connected with port 0, and control pins are connected with port 3,link is given below,
http://www.8052.com/tutlcd.phtml

so you check the connections made for C program that whether lcd is connected with the same ports or not, I think that after changing the connections you can solve this problem.