Thanks for answer.
As my swift server is serverd as a proxy server, I can look at swift proxy-server's log which I have mention on my post, it report like this :

Mar 1 20:43:48 localhost journal: proxy-logging 192.168.1.1 192.168.1.1 01/Mar/2016/20/43/48 GET /auth/v1.0 HTTP/1.0 401 - Mozilla/5.0%20%28Windows%20NT%206.1%3B%20WOW64%29%20AppleWebKit/537.36%20%28KHTML%2C%20like%20Gecko%29%20Chrome/28.0.1500.72%20Safari/537.36 - - 131 - txbfc24355780143568445c4ddf5d774e3 - 0.0003 -
Mar 1 20:43:48 localhost journal: tempauth - 192.168.1.1 01/Mar/2016/20/43/48 GET /auth/v1.0 HTTP/1.0 401 - Mozilla/5.0%20%28Windows%20NT%206.1%3B%20WOW64%29%20AppleWebKit/537.36%20%28KHTML%2C%20like%20Gecko%29%20Chrome/28.0.1500.72%20Safari/537.36 - - - - txbfc24355780143568445c4ddf5d774e3 - 0.0007



It seems there are some unrecognized char are contained in the request which nginx send to swift server .while I use curl command to send request, it works fine, swift server log report like this :

Mar 1 18:38:44 localhost journal: proxy-server 192.168.1.1 192.168.1.1 01/Mar/2016/18/38/44 GET /auth/v1.0 HTTP/1.0 200 - curl/7.47.1 - - - - txc35cdcf0cc6f4d938e57772da694352a - 0.0015 -
Mar 1 18:38:44 localhost journal: proxy-server - 192.168.1.1 01/Mar/2016/18/38/44 GET /auth/v1.0 HTTP/1.0 200 - curl/7.47.1 - - - - txc35cdcf0cc6f4d938e57772da694352a - 0.0020


It seems swift cannot recognize the request from my nginx which has configed with an addictional module named ngx_http_auth_request_module. Maybe nginx was not passes right user and password to swift, but i have no idea which way to figure it out.

Best,
Amy