Single event upset (SEU) is one of the most common faults caused by the radiation environment of space instrument, and solar activity is an important factor affecting the space radiation environment of the space instrument. In order to analyze the effect of solar activity on the single event upset of space instrument in this paper, the relation between the solar activity changes of the 24th solar cycle and the onorbit single event upset data are studied, which are collection from 48 instruments in three different low orbit satellites during March 2010 to April 2015. By combining the sunspot and SEU we found a negative relation between the solar activity with the SEU and the SEU curve after a specified delay had a strong correlation with the sunspot curve during the activity period, the lower the orbit, the better the correlation. This finding provides an important reference value for the prediction of the single event upset of space instrument. The reliability of the instrument in the space environment can be predicted and evaluated by observing the change of the solar activity for a specific period of time, so as to avoid the space radiation risk by designing the anti radiation reinforcement scheme.