Traditional methods for generating beams with a long depth of focus， such as spatial light modulator and a combination of positive and negative lens， have several limitations， including a large size of optical elements， difficult integration with micro-nano optics and others. This makes the application of optical devices in aviation areas challenging. Thus， it is necessary to develop a method for generating beams with a long depth of focus beam， and fabricating an optical element with a simple structure， compact size， and good imaging quality. In this paper， we achieve this by using continuous cubic phase plate modulation. A phase plate with high dimensional accuracy （108 μm in diameter， 1.1 μm in height） and adjustable focal length （50-150 μm） and focal depth range （100-600 μm） is fabricated via femtosecond laser direct writing technology. The optical test of the phase plate demonstrates its long depth of focus and imaging ability. This method indicates new avenues in high performance integrated optics， micro/nano-optics manufacturing， and laser micro/nano manufacturing for aeronautical science and technology.