The process of a relaxation oscillation can be described by complex circle maps

which reduce to single inverse circle map when the falling time of the process in the oscillation is zero. The order of map is determined by the function form of the modulation signal. Supercritical behaviors of the oscillation ave studied experimentally and numerically. Two scaling laws

namely s（f） ∝f-δ and τ∝|f-fc |-γ are certified

in which for single circle map the exponent γ = 0.5 and does not change with the order of map

but for complex circle maps

there are two values in γ and both the scaling exponents S and γ2 increase when the order of the map is getting larger.