An ultrasonic transducer, comprising: a piezoelectric-vibrator assembly, having a first side and a second side opposite to the first side, and comprising one or more piezoelectric vibrators; an acoustic matching layer, arranged on the first side of the piezoelectric-vibrator assembly; a heat sink, arranged on the second side of the piezoelectric-vibrator assembly and comprising: a body, substantially in shape of a column and having a central axis; a head portion, disposed at one end of the body and facing towards the piezoelectric-vibrator assembly; a tail portion, disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly, wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion, the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink. a piezoelectric-vibrator assembly, having a first side and a second side opposite to the first side, and comprising one or more piezoelectric vibrators; an acoustic matching layer, arranged on the first side of the piezoelectric-vibrator assembly; a heat sink, arranged on the second side of the piezoelectric-vibrator assembly and comprising: a body, substantially in shape of a column and having a central axis; a head portion, disposed at one end of the body and facing towards the piezoelectric-vibrator assembly; a tail portion, disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly, wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion, the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink. a body, substantially in shape of a column and having a central axis; a head portion, disposed at one end of the body and facing towards the piezoelectric-vibrator assembly; a tail portion, disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly, wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion, the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink.