A welding method of butted profile, comprising: assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together, wherein the plurality of profiles with a backing bar comprise a profile with a single backing bar and a profile with double backing bars, and wherein the assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together comprises lapping and jointing one end of the profile without backing bars with an end with backing bar of the first profile with a backing bar, and lapping and jointing the other end of the profile without backing bars with an end with backing bar of the second profile with a backing bar; characterized in that, the method further comprises: welding two lateral parts of the profile without backing bars with the corresponding first profile with a backing bar and the second profile with a backing bar simultaneously; before the assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together, further comprising: welding adjacent profiles with a single backing bar together; if the butted profile comprises the adjacent profiles with a single backing bar; and/or welding a profile with double backing bars with a profile with a single backing bar adjacent to the profile with double backing bars together, if the butted profile comprises the profile with double backing bars and the profile with a single backing bar adjacent to the profile with double backing bars. assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together, wherein the plurality of profiles with a backing bar comprise a profile with a single backing bar and a profile with double backing bars, and wherein the assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together comprises lapping and jointing one end of the profile without backing bars with an end with backing bar of the first profile with a backing bar, and lapping and jointing the other end of the profile without backing bars with an end with backing bar of the second profile with a backing bar; characterized in that, the method further comprises: welding two lateral parts of the profile without backing bars with the corresponding first profile with a backing bar and the second profile with a backing bar simultaneously; before the assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together, further comprising: welding adjacent profiles with a single backing bar together; if the butted profile comprises the adjacent profiles with a single backing bar; and/or welding a profile with double backing bars with a profile with a single backing bar adjacent to the profile with double backing bars together, if the butted profile comprises the profile with double backing bars and the profile with a single backing bar adjacent to the profile with double backing bars. welding two lateral parts of the profile without backing bars with the corresponding first profile with a backing bar and the second profile with a backing bar simultaneously; before the assembling a profile without backing bars with a first profile with a backing bar and a second profile with a backing bar of a plurality of profiles with a backing bar together, further comprising: welding adjacent profiles with a single backing bar together; if the butted profile comprises the adjacent profiles with a single backing bar; and/or welding a profile with double backing bars with a profile with a single backing bar adjacent to the profile with double backing bars together, if the butted profile comprises the profile with double backing bars and the profile with a single backing bar adjacent to the profile with double backing bars.