Picosecond cyclization reaction dynamics of furan-based photochromic diarylethenes with thiosemicarbazone side-chains were studied by femtosecond transient absorption spectroscopy. The monitored ring-closing reaction in the time range of 0 divided by 1100ps is characterized by two main stages. First stage proceeds during the first 1.1 ps and is associated mainly with redistribution of - molecular orbitals of excited open-ring molecules which consequently leads to the formation of excited closed-ring molecules. During the next 300ps, a long-term relaxation via vibrational cooling of closed-ring form occurs. The obtained relaxation dynamics curve was fitted by an exponential decay function with 68ps time constant.