An ultra-thin surface mounted LED lamp having surface emitting light, comprising: a housing, the housing comprising a bottom and a side wall extending from the bottom; a light module received in the housing, the light module being striped and comprising a plurality of LED chips, a light emitting direction of the light module being perpendicular to the side wall of the housing; a reflection film mounted in the housing, the reflection film being a diffusion reflective film and mounted on the bottom of the housing; a light guide plate arranged in the housing, an edge of the light guide plate being provided with a diffusion groove at a position opposite to each of the LED chip, the light guide plate comprising an light receiving wall configured for receiving the emitted light of the light module and a reflecting wall configured for reflecting light; characterized in that: a maximum distance between the two LED chips at a head and tail of the light module accounting for two thirds of the total circumference of the side walls; the diffusion groove is V-shaped and a bottom of the V-shaped diffusion groove is circular, a length of the light receiving wall is equal to the maximum distance between the two LED chips at the head and tail of the light module, the reflective wall is configured to have a reflecting layer provided thereon; and said ultra-thin surface mounted LED lamp further comprises a plurality of light guide points provided on the light guide plate and sandwiched between the reflection film and the light guide plate, the light guide points being spaced apart circular dots, the total area of which is 60% to 65% of the total area of the light guide plate. a housing, the housing comprising a bottom and a side wall extending from the bottom; a light module received in the housing, the light module being striped and comprising a plurality of LED chips, a light emitting direction of the light module being perpendicular to the side wall of the housing; a reflection film mounted in the housing, the reflection film being a diffusion reflective film and mounted on the bottom of the housing; a light guide plate arranged in the housing, an edge of the light guide plate being provided with a diffusion groove at a position opposite to each of the LED chip, the light guide plate comprising an light receiving wall configured for receiving the emitted light of the light module and a reflecting wall configured for reflecting light; characterized in that: a maximum distance between the two LED chips at a head and tail of the light module accounting for two thirds of the total circumference of the side walls; the diffusion groove is V-shaped and a bottom of the V-shaped diffusion groove is circular, a length of the light receiving wall is equal to the maximum distance between the two LED chips at the head and tail of the light module, the reflective wall is configured to have a reflecting layer provided thereon; and said ultra-thin surface mounted LED lamp further comprises a plurality of light guide points provided on the light guide plate and sandwiched between the reflection film and the light guide plate, the light guide points being spaced apart circular dots, the total area of which is 60% to 65% of the total area of the light guide plate. a maximum distance between the two LED chips at a head and tail of the light module accounting for two thirds of the total circumference of the side walls; the diffusion groove is V-shaped and a bottom of the V-shaped diffusion groove is circular, a length of the light receiving wall is equal to the maximum distance between the two LED chips at the head and tail of the light module, the reflective wall is configured to have a reflecting layer provided thereon; and said ultra-thin surface mounted LED lamp further comprises a plurality of light guide points provided on the light guide plate and sandwiched between the reflection film and the light guide plate, the light guide points being spaced apart circular dots, the total area of which is 60% to 65% of the total area of the light guide plate.