Hi, firstly im newbie, hello everyone. My motherlanguage is not English so im sorry about it.

I'm using deepin for 2 or 3 months. I bought a new monitor and i want to use both of them. I have 2 graphic cards. One of them is amd radeon r7 and the second one is in motherboard intel xeon e3-1200. So it means i have 2 ports to connect monitors. I was using dual monitors in windows with iGpu Multimonitor settings in bios, and it was working well. But in deepin, i cant use it. I did everything same as windows but it doesnt make it double.

After selecting deepin os, i see "DEEPIN" logo both of my monitors and after 5-10 second one of them(igpu, motherboard intel) is going sleeping mode and i can only use other one.

How can i use dual monitor in deepin os. Sorry for my English again. Thank you

What xrandr tells you?

Screen 0: minimum 320 x 200, current 1440 x 900, maximum 16384 x 16384
HDMI-1 disconnected (normal left inverted right x axis y axis)
DVI-0 disconnected (normal left inverted right x axis y axis)
VGA-1 connected primary 1440x900+0+0 (normal left inverted right x axis y axis) 410mm x 256mm
1440x900 59.90*+ 74.98
1280x1024 75.02 60.02
1024x768 75.03 70.07 60.00
800x600 72.19 75.00 60.32 56.25
640x480 75.00 72.81 59.94
720x400 70.08

i think it see only one card. Also i installed deepin graphics card driver application, it was saying intel and amd cant run same time or something like that but after some changes in bios it says AMD.

In Linux world there are configuration files, and there are GUI applications which can make editing them easy. In your case there seems to be no GUI utility is able to set it up the way you want. So you need to resort editing configuration files by hand. You need good internet search skills to find a case like yours, here's the start:
https://duckduckgo.com/?q=Linux+dual...b=v23__&ia=web
Indeed, there is another way, reading up on Xorg documentation and writing the configuration from scratch.