Wire-arc　additive　manufacturing　(WAAM)　has　been　considered　as　one　of　the　potential　additive-manufacturing　technologies　to　fabricate　large　components.　However,　its　industrial　application　is　still　limited　by　the　existence　of　stress　and　distortion.　During　the　process　of　WAAM,　the　scanning　pattern　has　an　important　influence　on　the　temperature　field,　distortion　and　final　quality　of　the　part.　Four　kinds　of　deposition　patterns,　including　sequence,　symmetry,　in-out　and　out-in,　were　designed　to　deposit　H13　steel　in　this　study.　An　in　situ　measurement　system　was　set　up　to　record　the　temperature　history　and　the　progress　of　accumulated　distortion　of　the　parts　during　deposition.　An　S　value　was　proposed　to　evaluate　the　distortion　of　the　substrate.　It　was　shown　that　the　distortion　of　the　part　deposited　by　sequence　was　significantly　larger　than　those　of　other　parts.　The　distortion　deposited　by　the　out-in　pattern　decreased　by　68.6%　compared　with　sequence.　The　inherent　strain　method　and　strain　parameter　were　introduced　to　expose　the　mechanism　of　distortion　reduction　caused　by　pattern　variation.