Abstract: Two kinds of coating consisted predominantly of oxides of Na,K and Ti were formed on the solid wire by nano-coating technology in the paper.The signals of arc voltage and current were collected by of the analysator Hannover.By analysis of the voltage probability density distribution,current probability density distribution,∑n(U_s) and ∑n(I_s),∑n(U_s) and ∑n(I_s),the usability of the three kinds of solid wire were compared.The experimental results show that the droplet size of two kinds of coating solid wires are smaller than un-coating solid wire and the droplet size of solid wire whose coating includes boron is the smallest in three solid wires.The reasons are that the surface tension of the droplet is reduced and the electromagnetic force in axial direction is increased due to the coating.In addition,the reason why the droplet size of solid wire whose coating includes boron is smallest is that boric oxide can drastically reduce surface tension.