Have you got a link to where you bought it from? Does it have an FTDI or CH340 chip on it?
it was given to me by my manager, however he told me it was bought on gearbest.com it has a CH340 chip
In which case see this thread here.
Had heaps of problems here, tried the chinese drivers CH341_SER - but as the date suggested (2013) they didn't work with my very late model Mac running 10.10.4. I tried the FTDI drivers and they didn't work either. I had a look and found commercial download (cost about £5) and it worked perfectly (yes I've tested it with a tiny sketch). I'm not working for the commercial firm, and yes I bought a cheap chinese nano - but I've seen heaps of woe on this forum and it worked for me - Drivers are from Repleo and appear as /dev/cu.Repleo-CH341-00001014 on my mac.
YMMV - but I'm sure a lot of folks have given up on this and the device itself works just great - just needs some drivers specially for the mac. I guess XP, Win8 or older macs are probably just fine.
Got the same problem, I bought a nano in GearBest and got one with CH340 driver. Got the driver from: http://www.codenuke.net/2015/01/nodemcu-install-ch340-usb-to-serial-for-yosemite.html and it worked
Hope this one extra step in mac recovery mode terminal might help someone. This did the thing for me)
http://www.homautomation.org/2015/02/05/how-to-use-arduinos-with-ch340g-ch341g-serialusb-ftdi-chip/
I have the same problem with an Imac and El Capitan. I have it with an original UNO R3, I can see the board in the "About this mac" -- System report, and also i can see the usb port in the arduino IDE, but when i try to upload, sometimes nothing happen, or sometimes the system do not respond anymore, until i restart.
I have tried to unable de scr protection, install new drivers for the usb, and nothing.
Any help.
Excuse my english, i´m not an english speaker
PD: I have tried with a Pro Mini with the same result
fmod:
Got the same problem, I bought a nano in GearBest and got one with CH340 driver. Got the driver from: http://www.codenuke.net/2015/01/nodemcu-install-ch340-usb-to-serial-for-yosemite.html and it worked
Thank you so much! I have tried almost everything with my Chinese nano from aliexpress, and finally drivers from codenuke worked fine!
fmod Many thanks your link http://www.codenuke.net/2015/01/nodemcu-install-ch340-usb-to-serial-for-yosemite.html got the problem sorted.
Same result as neilrcooper... Thank you very, very much fmod. I've been trying to solve this problem for a few days now. Now I can play! 
Hello! After looking around for a while I found that my Ebay Clone worked flawlessly with this website.
Hopefully this works for you too.
I checked the USB/Serial chip on my cheap Chinese Nano clone board and found out it's a CH340 (instead of PL2302, used in official boards).
Followed the instructions given at http://www.instructables.com/id/Arduino-Nano-CH340/
And downloaded the drivers for my El Capitan 10.11.5 at http://www.wch.cn/download/CH341SER_ZIP.html
Things are working fine now.
(instead of PL2302, used in official boards).
Official boards use FT232 from FTDIchip.com
OSX Sierra confirmed working with Nano from eBay/DX.com and CH340 serial chipset with the following driver
Regards