Connection with two blocking tcp sockets. when i send message with high frequency, some package were lost. what''s the reason and how could i solve the problem?

Your packets are not lost, they''re melt together due to the Nagle''s Algorithm. You have to write a protocol able to cut down those melted messages before working with them.

Write down everything received from the server in a log file, you will understand easily how to deal with that.