This　study　presents　a　low-power　multi-lead　wearable　electrocardiogram　(ECG)　signal　sensor　system　design　that　can　simultaneously　acquire　the　electrocardiograms　from　three　leads,　I,　II,　and　V1.　The　sensor　system　includes　two　parts,　an　ECG　test　clothing　with　five　electrode　patches　and　an　acquisition　device.　Compared　with　the　traditional　12-lead　wired　ECG　detection　instrument,　which　limits　patient　mobility　and　needs　medical　staff　assistance　to　acquire　the　ECG　signal,　the　proposed　vest-type　ECG　acquisition　system　is　very　comfortable　and　easy　to　use　by　patients　themselves　anytime　and　anywhere,　especially　for　the　elderly.　The　proposed　study　incorporates　three　methods　to　reduce　the　power　consumption　of　the　system　by　optimizing　the　micro　control　unit　(MCU)　working　mode,　adjusting　the　radio　frequency　(RF)　parameters,　and　compressing　the　transmitted　data.　In　addition,　Huffman　lossless　coding　is　used　to　compress　the　transmitted　data　in　order　to　increase　the　sampling　rate　of　the　acquisition　system.　It　makes　the　whole　system　operate　continuously　for　a　long　period　of　time　and　acquire　abundant　ECG　information,　which　is　helpful　for　clinical　diagnosis.　Finally,　a　series　of　tests　were　performed　on　the　designed　wearable　ECG　device.　The　results　have　demonstrated　that　the　multi-lead　wearable　ECG　device　can　collect,　process,　and　transmit　ECG　data　through　Bluetooth　technology.　The　ECG　waveforms　collected　by　the　device　are　clear,　complete,　and　can　be　displayed　in　real-time　on　a　mobile　phone.　The　sampling　rate　of　the　proposed　wearable　sensor　system　is　250　Hz　per　lead,　which　is　dependent　on　the　lossless　compression　scheme.　The　device　achieves　a　compression　ratio　of　2.31.　By　implementing　a　low　power　design　on　the　device,　the　resulting　overall　operational　current　of　the　device　is　reduced　by　37.6%　to　9.87　mA　under　a　supply　voltage　of　2.1　V.　The　proposed　vest-type　multi-lead　ECG　acquisition　device　can　be　easily　employed　by　medical　staff　for　clinical　diagnosis　and　is　a　suitable　wearable　device　in　monitoring　and　nursing　the　off-ward　patients.