Insight problem solving is the result of complex interactions of multiple cognitive activities and neural regulation. In addition, unconscious processing is considered important to insight problem solving, due to the difficulty in capturing, few studies have directly probed this process. The present research recruited 37 participants, recorded the EEG activities when they completed the compound remote association task. By comparing the microstates (the topographic maps formed by the clusters are used to reveal the cognitive processes that may occur at the millisecond level) of the insight, non-insight and unresolved condition in the different stages, the main results show that: (1) under the insight condition, microstate C(reflecting a part of the default mode network) shows a higher rate of occurrence and more frequent transition with microstate A(related to the cognitive process of speech information processing) and microstate D(reflecting attention and input, related to executive function). (2) microstate B (related to visual processing) occurs significantly more frequently at the beginning of both types of successful problem solving, but only in each stage of the non-insight condition. The current research results indicate that the time series of microstates corroborate the distinct neural responses observed under different problem-solving conditions at the electrophysiological level. The successful resolution of a problem depends on an adequate representation of the problem and the active participation of executive function. More importantly, when comparing the two conditions for successful problem solving, microstate C, associated with the default mode network, is only captured under the insight condition. This indicates that during insight problem solving, the brain may be engaging in unconscious processes that are not directly related to the current task.