Flame height is a key parameter which describes the flame characteristic and flame combustion condition.The most popular method to detect it is ocular estimate at present.As weak flame has characteristics of low bright

low signal-to-noise ratio and vague outline

ocular estimation won’t work anymore

and the conventional image analysis method is highly depends on the threshold value.In order to solve these problems

after extracting incomplete flame edge by using the convention image processing method

multi-parameter model of flame contour is established to calculated flame height.The experimental result indicate that this algorithm has strong anti-jamming ability.Compared with the conventional method

the algorithm has character such as high precision

low dependence of threshold value and good consistency.