"I want to connect RD &WR siganls of MCU to 3 8255 chips, one EPROM,one SRAM. Can I ? If not what I have to do?"
"I have connected up to 3 chips to the 8051 external bus"

All chips are not the same, you can not connect 3 74s chips to a '51, but you'll have no problem with many 74HC.

re 8255:
first, why do you use such antique chips.
second, if they are 8255 you can not connet 3, but if they are 82c55 you can.

Get up to date, throw the 8255 out.

Erik