Parallel computation is an efficient method for speeding up electromagnetic (EM) optimization. This paper reviews the recent advanced parallel EM optimization approaches to microwave circuits. Recent techniques are discussed in this paper which include parallel EM optimization with coarse models and parallel EM optimization without available coarse models. Using parallel techniques, multiple EM data are generated simultaneously. The surrogate model is then trained to be valid in a larger region using multiple EM data, thus speeds up the entire EM optimization.