The light curves of optical outbursts observed in blazar OJ287 during 1983-2015 are analyzed and model-simulated to investigate the nature of its optical radiation. It is shown that the December/2015 outburst has its multi-wavelength variability behavior very similar to that of the synchrotron outburst in March/2016, indicating that the 2015 outburst may originate from synchrotron process. In combination with helical motion of superluminal components, the precessing jet nozzle scenario previously proposed is used to model-simulate the lightcurves of all the optical outbursts discussed. The optical light curves for both periodic and non-periodic outbursts observed in blazar OJ287 can be well interpreted in terms of lighthouse effect due to the helical motion of superluminal optical knots, showing their common origin in synchrotron process. A coherent and compatible framework is tentatively suggested to understand the entire phenomena in OJ287. The double-peak structure of the periodic outbursts might be explained by invoking the cavity-accretion flare models for comparable-mass binary systems in eccentric motion.