This paper applies the decomposition theory to examine the seasonal fluctuation, cycle and trend on processed fishery products (canned products, frozen and cold storage products, dried-salted products, others products) value for Taiwan during 1995–2005. Our estimation results that that processed fishery products time-series fluctuation was a significantly seasonal affect apparently that the higher level at January. Except the canned products, the lower levels at July to August. Then Hodrick–Prescott (HP) filter is applied to decompose the trend and cycle component of the processed fishery products series. The estimation results indicate that have random fluctuations and indistinguishable of period cycles At least, we found the similarity fluctuations between cold storage products and dried-salted products time-series... The estimation results are of policy implication to the development of processed fishery products market in Taiwan.