The present invention provides a Soft Plasma Cleaning (SPC) system (30, 130, 230) including a Guided Soft-Plasma Cleaning (G-SPC) (30). The SPC system is a non-thermal, low temperature process and operable at atmosphere pressure, in both air and liquid medium. In an embodiment, a feedstock gas (40) is supplied to provide a discharging fluid (50) in the cleaning chamber (34). A plasma guiding and amplifying component (52) guides and expands the discharging fluid to cover a large ablation area over the workpiece (32), thereby also suppressing ion and electron bombardment damage or etching. The plasma guiding and amplifying component (52) may be formed with dielectric plates or tubes (37, 56, 58), with each dielectric having an aperture (37a, 56a, 58a). The electric field and ion energy in the cleaning chamber can be additionally controlled via a floating electrode (160, 160a), so as to suppress plasma damage during SPC.