A kind of multi-gear pump based on oval gear is proposed

and its flow characteristics are discussed.The radial size of the oval gear varies with its rotation angle continuously

making the volume between pump shell and the meshed gears change during rotation

and these changes can be used to send liquid forward.Although being simple in structure

the flow fluctuation of oval gear pump with two gears is great

which makes it unavailable in fact.The two oval gear pumps are used to compose parallel gear pump in structure can make the fluctuations of two pump outputs compensate each other

the flow fluctuations can be greatly decreased

and an available gear pump is obtained.