The　models　and　parameters　of　harmonic　source　are　the　main　factors　that　affect　the　calculation　accuracy　of　harmonic　flow.　Harmonic　source　was　divided　into　linear　load　and　non-linear　load　and　then　modelled　separately.　The　algorithm　flowcharts,　coupling　method,　decouple　method　and　linear　method,　were　analyzed　with　power　source　model,　current　source　model　and　current　source-impedance　model　correspondingly.　The　frequency　response　of　those　models　was　compared　with　a　simple　example.　It　indicates　that　the　model　of　linear　load　and　its　affect　in　harmonic　frequency　are　the　key　factors　influencing　computational　accuracy　of　harmonic　power　flow.　Then　an　example　of　harmonic　flow　in　a　3-bus　distributed　system　was　introduced　which　shows　the　dramatic　difference　among　the　results　of　harmonic　power　flow　resulting　from　those　models.　It　suggests　that　the　on-line　monitor　should　be　continued　long　enough　to　analyze　the　operating　character　of　harmonic　source　and　choose　the　model　appropriately.　©　2016,　The　Editorial　Board　of　Journal　of　System　Simulation.　All　right　reserved.