The traditional linear variable filter hyperspectral imagers put the linear variable filter in front of the detector window. Due to the difference in the position of the linear variable filter and the detector focal plane， the spectral resolution will be reduced. In order to solve this problem， the hyperspectral imager based on linear variable filter is designed with telescope system， linear variable filter， relay system and detection system. The linear variable filter is placed on the focal plane of the telescope system， and the relay system is to image the linear variable filter on the target surface of the detector so that the linear variable filter coincides with the focal plane of the detector. For the hyperspectral imager system， the spectral range is 400~700 nm， the number of spectrum bands is 31， the spectral resolution is 10 nm， the field of view angle is ±8° and the focal length is 55 mm. After the design and construction of the sample machine， spectral calibration and application experiments is carried out with good results. Compared with traditional hyperspectral imager systems using prisms or gratings to split light， the proposed system doesn't need a collimation system， and has the advantages of small size， light weight and high luminous flux， which can provide a reference for the miniaturization of hyperspectral imagers.