The observation data by visibility meter in 2014 in national basic station in Panzhihua was compared with artificial observation haze days in recent 5 years. The analysis showed that,replace the manual observation visibility with visibility sensor,the haze days increased significantly. When △P24 0,it was easier to form haze. After the haze apperance,the visibility did not change significantly and continued for a long time. It can eliminate the human error,really reflect the atmospheric conditions,and meet the business requirements.