A water-proof decorative lamp, comprising: a light source body, comprising a light-emitting chip and a packaging body, wherein the light-emitting chip is arranged in the packaging body and the light-emitting chip is provided with two pins extending out of the packaging body; connecting wires, each comprising a conductive wire and an insulating layer, wherein a side wall of the conductive wire is covered with the insulating layer, the conductive wire located at one end of the connecting wire protrudes out of the insulating layer to form a connector, and the two pins are respectively connected with the connectors; and a water-proof component, comprising an isolating column and a sleeve, wherein the isolating column is disposed between the two pins so as to separate the two pins from each other and separate the two connectors from each other, one end of the sleeve is arranged around the insulating layer near the connector, and the other end of the sleeve is arranged around the packaging body near the pin, to cover the connector and the pin, the isolating column is made of a hot melting material, and the sleeve is made of a heat-shrinkable material; wherein the water-proof decorative lamp further comprises a lamp holder and a light transmitting cover, the lamp holder is provided with an installing channel with an opening, the light source body is arranged in the installing channel, a notch for passing the connecting wire is arranged on a bottom wall of the installing channel, the light transmitting cover is snap- fitted with the lamp holder, and the light transmitting cover is configured for covering the installing channel; characterized in that the water-proof decorative lamp further comprises a positioning block, the positioning block is arranged at a bottom portion of the isolating column and is located between the connecting wires, positioning surfaces located in the installing channel are arranged at both sides of the lamp holder, and two sides of the positioning block are abutted against the positioning surfaces respectively. a light source body, comprising a light-emitting chip and a packaging body, wherein the light-emitting chip is arranged in the packaging body and the light-emitting chip is provided with two pins extending out of the packaging body; connecting wires, each comprising a conductive wire and an insulating layer, wherein a side wall of the conductive wire is covered with the insulating layer, the conductive wire located at one end of the connecting wire protrudes out of the insulating layer to form a connector, and the two pins are respectively connected with the connectors; and a water-proof component, comprising an isolating column and a sleeve, wherein the isolating column is disposed between the two pins so as to separate the two pins from each other and separate the two connectors from each other, one end of the sleeve is arranged around the insulating layer near the connector, and the other end of the sleeve is arranged around the packaging body near the pin, to cover the connector and the pin, the isolating column is made of a hot melting material, and the sleeve is made of a heat-shrinkable material; wherein the water-proof decorative lamp further comprises a lamp holder and a light transmitting cover, the lamp holder is provided with an installing channel with an opening, the light source body is arranged in the installing channel, a notch for passing the connecting wire is arranged on a bottom wall of the installing channel, the light transmitting cover is snap- fitted with the lamp holder, and the light transmitting cover is configured for covering the installing channel; characterized in that the water-proof decorative lamp further comprises a positioning block, the positioning block is arranged at a bottom portion of the isolating column and is located between the connecting wires, positioning surfaces located in the installing channel are arranged at both sides of the lamp holder, and two sides of the positioning block are abutted against the positioning surfaces respectively.