  Globular clusters harbor numerous millisecond pulsars, but long-period
pulsars ($P \gtrsim 100$ ms) are rarely found. In this study, we employed a
fast folding algorithm to analyze observational data from multiple globular
clusters obtained by the Five-hundred-meter Aperture Spherical radio Telescope
(FAST), aiming to detect the existence of long-period pulsars. We estimated the
impact of the median filtering algorithm in eliminating red noise on the
minimum detectable flux density ($S_{\rm min}$) of pulsars. Subsequently, we
successfully discovered two isolated long-period pulsars in M15 with periods
approximately equal to 1.928451 seconds and 3.960716 seconds, respectively. On
the $P-\dot{P}$ diagram, both pulsars are positioned below the spin-up line,
suggesting a possible history of partial recycling in X-ray binary systems
disrupted by dynamical encounters later on. According to timing results, these
two pulsars exhibit remarkably strong magnetic fields. If the magnetic fields
were weakened during the accretion process, then a short duration of accretion
might explain the strong magnetic fields of these pulsars.
