A serial photonic channelized radio frequency (RF) measurement scheme is proposed and experimentally demonstrated. This scheme can be used for instantaneous multiple-frequency measurement and capturing key parameters of linear frequency modulation signals. Based on high-speed wavelength scanning, this photonic RF channelizer works serially in time domain, and each wavelength labels a certain RF channel. With only one low-bandwidth photodetector (PD), we can implement multiple channel RF frequency measurements, which have a much simpler structure compared with parallel channelized schemes using broadband filter-bank and multiple PDs.